With the ground hidden, the water IS visible from above (center 0.39,0.45,0.44 — teal-ish water). So the GROUND is covering the water! The ground mesh at the pond must have faces ABOVE the water surface, even though the vertices dip below.

The ground is a 130x130 grid of quads. The quads near the pond center are at -1.19, but quads further out rise to 0.35. When rendered from directly above, the ground quads at the pond's rim (0.35 > 0.25) should NOT cover the center... unless the ground quads in the pond area are warped such that they cross above the water.

The issue must be the terrain function creating a dish where the rim blocks the center from the camera. From directly above at z=20, looking straight down at (8,-7), the ray hits the water at 0.25 UNLESS the ground between the camera and that point is above 0.25 at the same (x,y). But straight down, the ray is vertical — the ground at (8,-7) is -1.19, water at 0.25 → water is hit first. UNLESS the ground mesh has a face whose projection overlaps (8,-7) at a height ABOVE 0.25 — i.e., the ground quads near the center might be distorted (folded) so that a quad from the rim overlaps the center region.

Hmm, wait — maybe the problem is the ground quads at the pond rim are tilted steeply, and their projected area covers the center. With a 130x130 grid over 68 units, each quad is ~0.52 units. The pond depression is 1.5 deep over 6.4 units radius — steep slopes. A steep quad at the rim could have its surface crossing the vertical line at (8,-7) above the water. But the rim is 6.4 units away from the center — the vertical line at the center is 6.4 units from the rim quads. A quad 6.4 units away can't cover the center.

Let me check: which faces of the ground mesh are above z=0.25 near the pond, and whether their XY projection covers the pond center. Actually, let me check the actual ground surface at the exact center with a ray cast.

import bpy, math
from mathutils import Vector

ground = bpy.data.objects['Ground']
# ray cast straight down from (8,-7,20)
hit, loc, n, idx = ground.ray_cast(ground.matrix_world.inverted() @ Vector((8,-7,20)),
                                   Vector((0,0,-1)))
print('hit', hit, 'loc', loc, 'face', idx)
if hit:
    f = ground.data.polygons[idx]
    print('face normal', f.normal, 'center z', sum(ground.data.vertices[i].co.z for i in f.vertices)/len(f.vertices))
    print('face verts z', [round(ground.data.vertices[i].co.z,3) for i in f.vertices])

# check ALL ground faces near pond: max z
import numpy as np
mesh = ground.data
maxz = -99; maxf = None
for f in mesh.polygons:
    zs = [mesh.vertices[i].co.z for i in f.vertices]
    zmax = max(zs)
    if zmax > maxz:
        maxz = zmax; maxf = f
print('ground max face z', round(maxz,3), 'center', maxf.center)

# count faces with center z > 0.25
cnt = 0
for f in mesh.polygons:
    if f.center.z > 0.25:
        cnt += 1
print('faces above 0.25:', cnt, 'of', len(mesh.polygons))