Its very hard to find the correct balance between too little information and too much.
The first lines are to go in the table and provide and instant idea the DM can improvise with. The rest is to to somewhere else and be remembered or looked up very quickly when necessary.
I could add a lot more descriptive crap to each of these but it would make them weigh more in the head and harder to use so I don't know.
Names are chosen as a combination of instantly descriptive, colourful and re-memorable. You are not meant to use them talking to the players. There is only one Fountain of Fontestorbe but a hundred caves that do that thing.
A SWIM GYM
Stepped stone pools and streams. Fordable. Descending.
A giant staircase. 3d4 pools. You can jump. 4 to 6 vertical feet. Swim/wade across. Anyone fighting can grapple and throw themselves down into the next pool as a free action, SO LONG AS THEY TAKE THE OTHER GUY WITH THEM.
Giant china plates with razor sides. Splayed like cards.
3d6 shallow pools rimmed by fragile, beautiful, razor sharp flowstone. Water knee high. Combat fumbles take chunks from the flowstone rims and crack them like crockery. Broken pools overflow in sequence.
Fallen stone or shattered faults. Cracked, crooked and flooded hip-width paths.
A nightmare of irregular cracked rocks, waist-high full of water. Imagine a bucket of smashed slates, piled. An ant to navigate them. You are the ant. The path-walls grow face-close. You turn side-on. Save against paralysis or freeze.
FOSSIL WATER LAKE
A plane of turquoise water, still and flat as glass.
Knee high, hip high, chest high, neck high, then out. (Do not tell players the depth.) The sky-coloured water makes you homesick and sad (the only blue thing you'll see.)
Roaring abyssal falls of unknowable depth.
A waterfall plunging beyond the lanterns rays. No way to know the depth before you climb. The sound drowns speech, no warning of sound. Ask who the players are looking at.
Clear, deep water. Full of house-sized marbles.
You can wade across this pool walking on the surface of the house-sized hyper-oolites that rest in it. They are perfect spheres with the tops almost breaching the surface. Draw circles and ask players where they are. Leap/swim from sphere to sphere.
FOUNTAIN OF FONTESTORBE
Smooth valved chamber, wet and regularly refills.
Flowing and curved like the inside of a brass wind instrument. Many tiny exits. Puddles and pools. Living fish flap. Will refill, violently and unstoppably every d30 minutes, forever.