-EDIT-**Upon further inspection, I've noticed map provided does not match the screenshot you posted. There are no blendmapped paths in the map provided.**

Mysterious:
-In gulley.txt: "Also added a small cave behind a waterfall"; There is no such cave.

Game-breaking:
-Add death material off the edge of the map... atm you can jump down, stand mid-air, then swim back up the waterfall. :/
-Either clip, or better yet resize, the collision box on the large trees. Atm, you can hide inside them.

Basic geometry:
-5 places where the geometry is broken beneath the top-most waterfall.
-5 spots with w/ unnecessary texture stretching at the bottom-most waterfall.
-multiple geometry hiccups inside the bottom-most waterfall.
-1 stray cube sticking out of the wall by the bottom-most waterfall.
-2 cubes w/ unnecessary texture stretching in the hole in the bridge thing on the lower section of the map.
-1 more cube w/ unnecessary texture stretching in the crack in the middle of the same bridge.
-1 spot where the bridge/log thing is mistextured as rock; seen in the other crack in the bottom if it.
-Round out the sharp 90 degree angles in the far corners of the map.(like near the cave entrances)

Detailing:
-Add sound; waterfalls, wind near the cave entrances, general ambiance
-Autograss that grassy/mossy texture, and tweak the grasscolour to match.
-Maybe use some smoke particles to hide the hard edge of the water at the bottom of the waterfalls.
-Maybe vscale that rock texture a bit larger, atm it looks very repetitive.(or just change the texture altogether)
-Use some texture blending. I'd recommend blending some moss on the top of that bridge/log thing on the lower section of the map.
-Better overall lighting. Don't be afraid to light those caves a little.
-Maybe add a little(just a little) fog and color it to match the skybox.