diff --git a/game/composition/vertical_slice/vertical_slice_root.gd b/game/composition/vertical_slice/vertical_slice_root.gd
index e53bbb3..eea2df7 100644
--- a/game/composition/vertical_slice/vertical_slice_root.gd
+++ b/game/composition/vertical_slice/vertical_slice_root.gd
@@ -130,10 +130,6 @@ func _start_dive() -> void:
 	if definition == null:
 		push_error("dive site definition %s cannot be loaded" % _selected_site_path)
 		return
-	var definition_error := definition.validation_error()
-	if not definition_error.is_empty():
-		push_error("dive site %s is invalid: %s" % [_selected_site_path, definition_error])
-		return
 	var world_scene := load(DIVE_WORLD_SCENE_PATH) as PackedScene
 	if world_scene == null:
 		return
diff --git a/game/domain/sites/terrain_height_field.gd b/game/domain/sites/terrain_height_field.gd
index 7866b17..610e34a 100644
--- a/game/domain/sites/terrain_height_field.gd
+++ b/game/domain/sites/terrain_height_field.gd
@@ -59,6 +59,11 @@ func maximum_elevation_m() -> float:
 	return _maximum_elevation_m
 
 
+## Row-major elevations (index = row * columns + column), the HeightMapShape3D layout.
+func elevations_m() -> PackedFloat32Array:
+	return _data.elevations_m
+
+
 func elevation_at_cell(column: int, row: int) -> float:
 	return _data.elevations_m[_data.index_of(_clamp_column(column), _clamp_row(row))]
 
diff --git a/game/world/sites/bathymetric_terrain_actor.gd b/game/world/sites/bathymetric_terrain_actor.gd
index a7fca5d..874aee4 100644
--- a/game/world/sites/bathymetric_terrain_actor.gd
+++ b/game/world/sites/bathymetric_terrain_actor.gd
@@ -116,12 +116,7 @@ func _build_collision() -> void:
 	var shape := HeightMapShape3D.new()
 	shape.map_width = _field.columns()
 	shape.map_depth = _field.rows()
-	var heights := PackedFloat32Array()
-	heights.resize(_field.columns() * _field.rows())
-	for row in _field.rows():
-		for column in _field.columns():
-			heights[row * _field.columns() + column] = _field.elevation_at_cell(column, row)
-	shape.map_data = heights
+	shape.map_data = _field.elevations_m()
 	_collision = CollisionShape3D.new()
 	_collision.name = "Collision"
 	_collision.shape = shape
diff --git a/game/world/sites/dive_site.gd b/game/world/sites/dive_site.gd
index 841d86d..d73d778 100644
--- a/game/world/sites/dive_site.gd
+++ b/game/world/sites/dive_site.gd
@@ -21,10 +21,10 @@ var _placeholder_count := 0
 func configure(definition: DiveSiteDefinition) -> String:
 	if definition == null:
 		return "dive site definition is missing"
-	var error := definition.validation_error()
-	if not error.is_empty():
-		return error
-	var terrain_error := _terrain.configure(definition.height_field())
+	var field := definition.height_field()
+	if field == null:
+		return "dive site definition is invalid"
+	var terrain_error := _terrain.configure(field)
 	if not terrain_error.is_empty():
 		return terrain_error
 	_definition = definition
diff --git a/tests/unit/run_site_domain_tests.gd b/tests/unit/run_site_domain_tests.gd
index 6715204..de0fdbe 100644
--- a/tests/unit/run_site_domain_tests.gd
+++ b/tests/unit/run_site_domain_tests.gd
@@ -7,7 +7,7 @@ const SitePlacement = preload("res://game/domain/sites/site_placement.gd")
 const SiteRoute = preload("res://game/domain/sites/site_route.gd")
 const DiveSiteDefinition = preload("res://game/domain/sites/dive_site_definition.gd")
 
-const TEST_COUNT := 38
+const TEST_COUNT := 39
 
 var _failures: Array[String] = []
 
@@ -83,10 +83,12 @@ func _test_terrain_data_validation() -> void:
 
 
 func _test_height_field_sampling() -> void:
-	var field := TerrainHeightField.from_data(_make_terrain(3, 4))
+	var data := _make_terrain(3, 4)
+	var field := TerrainHeightField.from_data(data)
 	_expect(field != null, "valid data yields a field")
 	if field == null:
 		return
+	_expect(field.elevations_m() == data.elevations_m, "elevations are exposed in row-major data order")
 	_expect(field.bounds_m().is_equal_approx(Rect2(-10.0, 100.0, 4.0, 6.0)), "bounds cover (columns-1) by (rows-1) cells")
 	_expect(field.cell_world_position(2, 3).is_equal_approx(Vector3(-6.0, -26.0, 106.0)), "cell position follows origin and cell size")
 	_expect(is_equal_approx(field.elevation_at(-10.0, 100.0), -20.0), "elevation at a vertex is exact")