Nice! Although I believe that Water hexes should be labelled with their Depth value (e.g. "Depth 0", "Depth 1", etc), rather than as a negative Level, as a negative Level could indicate a dry depression on land ... and the Level refers to the height of the water surface, rather than the bed.
Actually, LEVELs refer to 'dry heights'. be they UP or DOWN.
So, LEVEL 3 is three levels above 0
SUBLEVELS refer to negative levels and Depth refers to how deep, and that is based SURFACE LEVEL, not 0.
As an examlpe see the latest TUKAYYID maps:
A water hex that is above Level 0 will include a LEVEL number alongside a Depth number, signifying the Level of the surface of the water, and the Depth of the bottom of the hex.
So, a LEVEL 3, DEPTH 1 hex is 'Surface' is at level 3, and the Depth is 1 hex (at level 2).
Conversely, a SUBEVEL 4, Depth 2 hex, is a pool in a depression, where the surface is at Sublevel 4, and then bottom goes two more levels (ultimatle to a sublevel of 6)