diff --git a/workflow/internal/config.schema.yaml b/workflow/internal/config.schema.yaml
index 8dfa47f..b8edb2a 100644
--- a/workflow/internal/config.schema.yaml
+++ b/workflow/internal/config.schema.yaml
@@ -88,6 +88,19 @@ $defs:
         default: 1
         minimum: 0
 
+  gdalSettings:
+    description: Optional GDAL runtime configuration.
+    type: object
+    additionalProperties: false
+    properties:
+      geojson_max_obj_size_mb:
+        description: >
+          Maximum accepted size in megabytes for a single GeoJSON object read by
+          GDAL. Set to 0 to disable GDAL's single-object limit.
+        type: integer
+        default: 1024
+        minimum: 0
+
   scenario:
     type: object
     required:
@@ -222,6 +235,8 @@ properties:
     $ref: "#/$defs/crsSettings"
   voronoi_eez:
     $ref: "#/$defs/partialVoronoiEEZSettings"
+  gdal:
+    $ref: "#/$defs/gdalSettings"
   overture_release:
     description: |
       Overture data release to use. Two options are possible:
diff --git a/workflow/internal/settings.yaml b/workflow/internal/settings.yaml
index 2315670..b56599c 100644
--- a/workflow/internal/settings.yaml
+++ b/workflow/internal/settings.yaml
@@ -12,4 +12,6 @@ timeouts:
   connect_seconds: 15
   read_seconds: 30
   initial_retry_seconds: 5
+gdal:
+  geojson_max_obj_size_mb: 1024
 overture_release: "latest"
diff --git a/workflow/rules/_utils.smk b/workflow/rules/_utils.smk
index 6db3347..46c6036 100644
--- a/workflow/rules/_utils.smk
+++ b/workflow/rules/_utils.smk
@@ -35,6 +35,12 @@ def get_voronoi_eez_config(scenario: str) -> dict:
     return internal["voronoi_eez"] | user_overrides
 
 
+def get_gdal_config() -> dict:
+    """Get GDAL configuration with user overrides."""
+    gdal = internal["gdal"] | config.get("gdal", {})
+    return gdal
+
+
 def get_eez_file(scenario: str, country: str) -> str:
     """Build an EEZ filename reusable by scenarios with matching EEZ requests."""
     extra_eez = config["scenarios"][scenario]["countries"][country].get("extra_eez", [])
diff --git a/workflow/rules/download.smk b/workflow/rules/download.smk
index 6d28fd8..b4b3a54 100644
--- a/workflow/rules/download.smk
+++ b/workflow/rules/download.smk
@@ -26,6 +26,7 @@ rule download_geoboundaries:
         "../envs/shape.yaml"
     params:
         timeouts=internal["timeouts"],
+        geojson_max_obj_size_mb=get_gdal_config()["geojson_max_obj_size_mb"],
     message:
         "Downloading '{wildcards.country}_{wildcards.subtype}_{wildcards.release_type}' dataset from geoBoundaries."
     script:
@@ -42,6 +43,7 @@ rule download_gadm:
         "../envs/shape.yaml"
     params:
         timeouts=internal["timeouts"],
+        geojson_max_obj_size_mb=get_gdal_config()["geojson_max_obj_size_mb"],
     message:
         "Download '{wildcards.country}_{wildcards.subtype}' dataset from GADM."
     script:
diff --git a/workflow/scripts/_geo.py b/workflow/scripts/_geo.py
index 0e48a82..054c789 100644
--- a/workflow/scripts/_geo.py
+++ b/workflow/scripts/_geo.py
@@ -8,7 +8,7 @@
 import geopandas as gpd
 from pyproj import CRS
 from rasterio import warp
-from shapely import MultiPolygon, Polygon
+from shapely import MultiPolygon, Polygon, make_valid
 from shapely.geometry import GeometryCollection, mapping, shape
 from shapely.geometry.base import BaseGeometry
 
@@ -48,6 +48,36 @@ def extract_polygonal_geometry(
     return result
 
 
+def make_geometry_valid(geom: BaseGeometry | None) -> Polygon | MultiPolygon | None:
+    """Return a valid polygonal geometry, dropping empty or non-polygonal parts."""
+    result = None
+
+    if geom is not None and not geom.is_empty:
+        if isinstance(geom, (Polygon, MultiPolygon)) and geom.is_valid:
+            result = geom
+        else:
+            polygonal = extract_polygonal_geometry(make_valid(geom))
+            if (
+                polygonal is not None
+                and not polygonal.is_empty
+                and not polygonal.is_valid
+            ):
+                polygonal = extract_polygonal_geometry(make_valid(polygonal))
+
+            if polygonal is not None and not polygonal.is_empty and polygonal.is_valid:
+                result = polygonal
+
+    return result
+
+
+def make_geometries_valid(gdf: gpd.GeoDataFrame) -> gpd.GeoDataFrame:
+    """Apply polygonal geometry repair to a GeoDataFrame and drop empty results."""
+    result = gdf.copy()
+    result["geometry"] = result["geometry"].map(make_geometry_valid)
+    result = result.loc[result["geometry"].notna()]
+    return result
+
+
 def _rasterio_to_crs(gdf: gpd.GeoDataFrame, to_crs: CRS) -> gpd.GeoDataFrame:
     """CRS conversion using rasterio's more powerful toolset.
 
diff --git a/workflow/scripts/_schemas.py b/workflow/scripts/_schemas.py
index 1e878c3..3a066f1 100644
--- a/workflow/scripts/_schemas.py
+++ b/workflow/scripts/_schemas.py
@@ -1,7 +1,7 @@
 """Reusable schemas."""
 
 import geopandas as gpd
-from _geo import extract_polygonal_geometry
+from _geo import make_geometries_valid
 from pandera import pandas as pa
 from pandera.typing.geopandas import GeoSeries
 from pandera.typing.pandas import Series
@@ -37,14 +37,7 @@ class Config:
     @pa.dataframe_parser
     def fix_geometries(cls, gdf: gpd.GeoDataFrame) -> gpd.GeoDataFrame:  # type: ignore[misc]
         """Attempt to correct empty, malformed, or non-polygonal geometries."""
-        mask = gdf["geometry"].notna() & ~gdf["geometry"].is_empty
-        gdf = gdf.loc[mask].copy()
-
-        invalid = ~gdf.geometry.is_valid
-        gdf.loc[invalid, "geometry"] = gdf.loc[invalid, "geometry"].make_valid()
-
-        gdf["geometry"] = gdf["geometry"].apply(extract_polygonal_geometry)
-        return gdf.loc[gdf["geometry"].notna()]
+        return make_geometries_valid(gdf)
 
     @pa.check("geometry", element_wise=True)
     def check_geometries(cls, geom) -> bool:
diff --git a/workflow/scripts/_utils.py b/workflow/scripts/_utils.py
index 5cbf4f4..54d3905 100644
--- a/workflow/scripts/_utils.py
+++ b/workflow/scripts/_utils.py
@@ -5,6 +5,7 @@
 from pathlib import Path
 
 import geopandas as gpd
+import pyogrio
 import requests
 from matplotlib import pyplot as plt
 from matplotlib.axes import Axes
@@ -75,3 +76,11 @@ def download_file(url: str, path: Path, timeouts: DownloadTimeouts) -> None:
     raise RuntimeError(
         f"Maximum retries {max_retries} reached without a valid response"
     )
+
+
+def read_geojson_file(path: Path, geojson_max_obj_size_mb: int) -> gpd.GeoDataFrame:
+    """Read a GeoJSON file with the configured GDAL object-size limit."""
+    pyogrio.set_gdal_config_options(
+        {"OGR_GEOJSON_MAX_OBJ_SIZE": str(geojson_max_obj_size_mb)}
+    )
+    return gpd.read_file(path)
diff --git a/workflow/scripts/build_combined_area.py b/workflow/scripts/build_combined_area.py
index 6a99b9c..ca533bd 100644
--- a/workflow/scripts/build_combined_area.py
+++ b/workflow/scripts/build_combined_area.py
@@ -23,6 +23,7 @@ def remove_overlaps(gdf: gpd.GeoDataFrame, crs: dict[str, CRS]) -> gpd.GeoDataFr
     from the later geometry.
     """
     projected = _geo.to_projected_crs(gdf, crs["projected"])
+    projected = _geo.make_geometries_valid(projected)
 
     left_idx, right_idx = projected.sindex.query(
         projected.geometry, predicate="intersects"
@@ -51,13 +52,10 @@ def remove_overlaps(gdf: gpd.GeoDataFrame, crs: dict[str, CRS]) -> gpd.GeoDataFr
             continue
 
         geom = geom.difference(shapely.unary_union(cutters))
-        if geom is not None and not geom.is_empty and not geom.is_valid:
-            geom = shapely.make_valid(geom)
-
-        geoms[right] = geom
+        geoms[right] = _geo.make_geometry_valid(geom)
 
     projected["geometry"] = geoms
-    projected = projected.loc[projected.geometry.notna() & ~projected.geometry.is_empty]
+    projected = projected.loc[projected.geometry.notna()]
     result = _geo.to_geographic_crs(projected, crs["geographic"])
 
     return result
diff --git a/workflow/scripts/build_country.py b/workflow/scripts/build_country.py
index 25a7dd0..add471b 100644
--- a/workflow/scripts/build_country.py
+++ b/workflow/scripts/build_country.py
@@ -12,7 +12,7 @@
 import geopandas as gpd
 import pandas as pd
 from pyproj import CRS
-from shapely import make_valid, voronoi_polygons
+from shapely import voronoi_polygons
 from shapely.geometry import (
     GeometryCollection,
     LineString,
@@ -233,7 +233,7 @@ def _split_one_maritime(
         cells = gpd.GeoDataFrame(geometry=[], crs=crs)
     else:
         # Run Voronoi
-        maritime_geometry = make_valid(maritime_row.geometry)
+        maritime_geometry = maritime_row.geometry
         cells = gpd.GeoDataFrame(
             geometry=list(
                 voronoi_polygons(
@@ -243,7 +243,7 @@ def _split_one_maritime(
             ),
             crs=crs,
         )
-        cells["geometry"] = cells.geometry.map(make_valid)
+        cells = _geo.make_geometries_valid(cells)
 
         # Identify where each voronoi cell belongs
         cells = gpd.sjoin(
@@ -259,15 +259,18 @@ def _split_one_maritime(
 
         # Keep only cells on the maritime area and test for completeness
         cells["geometry"] = cells.geometry.intersection(maritime_geometry)
-        cells = cells.loc[~cells.geometry.is_empty & (cells.geometry.area > 0)]
+        cells = _geo.make_geometries_valid(cells)
+        cells = cells.loc[cells.geometry.area > 0]
         pieces = (
             cells[["assigned_shape_id", "geometry"]]
             .dissolve(by="assigned_shape_id", as_index=False)
             .rename(columns={"assigned_shape_id": "_assigned_shape_id"})
         )
-        # FIXME: check if rerunning `warp` is necessary to fix things near the antimeridian
-        pieces = _geo.to_projected_crs(pieces, crs)
-        uncovered_area = maritime_geometry.difference(pieces.geometry.union_all()).area
+        pieces = _geo.make_geometries_valid(pieces)
+        uncovered = _geo.make_geometry_valid(
+            maritime_geometry.difference(pieces.geometry.union_all())
+        )
+        uncovered_area = 0 if uncovered is None else uncovered.area
         if uncovered_area > voronoi_config.uncovered_area_tolerance:
             raise RuntimeError(
                 f"Voronoi split did not fully cover maritime shape {maritime_row.shape_id!r}. "
@@ -297,6 +300,7 @@ def split_maritime_by_shoreline_voronoi(
         return shapes, cells
 
     shapes_proj = _geo.to_projected_crs(shapes, crs["projected"])
+    shapes_proj = _geo.make_geometries_valid(shapes_proj)
     land = shapes_proj.loc[shapes_proj["shape_class"].eq("land")].copy()
     maritime = shapes_proj.loc[shapes_proj["shape_class"].eq("maritime")].copy()
     if maritime.empty:
@@ -326,7 +330,6 @@ def split_maritime_by_shoreline_voronoi(
             geometry="geometry",
             crs=crs["projected"],
         )
-    result.geometry = result.geometry.make_valid()
     result = _geo.to_geographic_crs(result, crs["geographic"])
     return result, cells
 
@@ -341,14 +344,16 @@ def build_country(
     # Reproject
     p_land = _geo.to_projected_crs(land, crs["projected"])
     p_marine = _geo.to_projected_crs(maritime, crs["projected"])
+    p_land = _geo.make_geometries_valid(p_land)
+    p_marine = _geo.make_geometries_valid(p_marine)
     # Remove contested zones
     p_marine = p_marine[p_marine["contested"].eq(False)].drop(columns="contested")
     # Give priority to EEZs
     p_land.geometry = p_land.geometry.difference(p_marine.geometry.union_all())
+    p_land = _geo.make_geometries_valid(p_land)
     combined = gpd.GeoDataFrame(
         pd.concat([p_land, p_marine], ignore_index=True), crs=crs["projected"]
     )
-    combined.geometry = combined.geometry.make_valid()
     return _geo.to_geographic_crs(combined, crs["geographic"])
 
 
diff --git a/workflow/scripts/download_gadm.py b/workflow/scripts/download_gadm.py
index e437a64..5ff2f94 100644
--- a/workflow/scripts/download_gadm.py
+++ b/workflow/scripts/download_gadm.py
@@ -10,7 +10,7 @@
 from typing import TYPE_CHECKING, Any
 
 import geopandas as gpd
-from _utils import DownloadTimeouts, download_file
+from _utils import DownloadTimeouts, download_file, read_geojson_file
 
 if TYPE_CHECKING:
     snakemake: Any
@@ -23,7 +23,7 @@
 
 
 def download_country_gadm(
-    country: str, subtype: str, timeouts: DownloadTimeouts
+    country: str, subtype: str, timeouts: DownloadTimeouts, geojson_max_obj_size_mb: int
 ) -> gpd.GeoDataFrame:
     """Attempts to download country GADM data in .json or zipped json."""
     last_error: Exception | None = None
@@ -35,7 +35,7 @@ def download_country_gadm(
                 tmp_path = Path(tmp_dir) / f"download.json{zip_ext}"
 
                 download_file(url, tmp_path, timeouts)
-                gdf = gpd.read_file(tmp_path)
+                gdf = read_geojson_file(tmp_path, geojson_max_obj_size_mb)
                 if gdf.empty:
                     raise RuntimeError(f"Downloaded empty GADM file from {url!r}.")
                 return gdf.to_crs(GADM_CRS)
@@ -51,7 +51,10 @@ def main():
     """Main snakemake process."""
     timeouts = DownloadTimeouts(**snakemake.params.timeouts)
     country = download_country_gadm(
-        snakemake.wildcards.country, snakemake.wildcards.subtype, timeouts
+        snakemake.wildcards.country,
+        snakemake.wildcards.subtype,
+        timeouts,
+        snakemake.params.geojson_max_obj_size_mb,
     )
     country.to_parquet(snakemake.output.path)
 
diff --git a/workflow/scripts/download_geoboundaries.py b/workflow/scripts/download_geoboundaries.py
index 526c80e..68ab2b7 100644
--- a/workflow/scripts/download_geoboundaries.py
+++ b/workflow/scripts/download_geoboundaries.py
@@ -10,7 +10,7 @@
 from typing import TYPE_CHECKING, Any
 
 import geopandas as gpd
-from _utils import DownloadTimeouts, download_file
+from _utils import DownloadTimeouts, download_file, read_geojson_file
 
 if TYPE_CHECKING:
     snakemake: Any
@@ -23,7 +23,11 @@
 
 
 def download_country_geoboundaries(
-    country: str, subtype: str, release_type: str, timeouts: DownloadTimeouts
+    country: str,
+    subtype: str,
+    release_type: str,
+    timeouts: DownloadTimeouts,
+    geojson_max_obj_size_mb: int,
 ) -> gpd.GeoDataFrame:
     """Download country data from geoBoundaries.
 
@@ -46,7 +50,7 @@ def download_country_geoboundaries(
         geojson_path = tmp_path / "download.geojson"
         download_file(geojson_url, geojson_path, timeouts)
 
-        gdf = gpd.read_file(geojson_path)
+        gdf = read_geojson_file(geojson_path, geojson_max_obj_size_mb)
         if gdf.empty:
             raise RuntimeError(
                 f"Downloaded empty geoBoundaries file from {geojson_url!r}."
@@ -64,6 +68,7 @@ def main():
         snakemake.wildcards.subtype,
         snakemake.wildcards.release_type,
         timeouts,
+        snakemake.params.geojson_max_obj_size_mb,
     )
     country.to_parquet(snakemake.output.path)