Underwater view
To view non-infinite water surfaces from underwater, you have to specify a collider. You can either use the box collider HDRP automatically provides or select a box collider in the scene to use for this purpose.
To view infinite water surfaces from underwater, you have to specify a Volume Depth.
If you look directly upward at the water surface from below, you may see a square border around the scene view. This is normal. It is because HDRP can only use screenspace data underwater.