It's time for pools of water or other liquids. I did a batch of four F-Series geomorphs this time, because I'm trying to finish 18 of the F and G series quickly and move on to a different geomorph topic entirely.
Geomorph F12 starts out the series with a couple simple pools that act as obstacles. The corridor on the left has a pool 10 feet across, almost certainly jumpable by the unencumbered, but trickier for those carrying a lot of gear or otherwise at a disadvantage (like dodging thrown rocks.) A chamber on the right is divided diagonally by another pool; it's a bit wider, so it may be a problem even for the unencumbered. Either pool may contain ordinary water, brackish or tainted water (no effect on swimmers, but not fit for consumption,) or something entirely other than water: acid (does damage,) alcohol (stings the eyes, but may be drinkable,) poison (deadly if ingested, perhaps even damaging for those who try to swim or get dunked.)
Geomorph F13 has something different: two long rectangular pools that run under some stone walls in the center of the geomorph. The stone walls create a large central room and two flanking corridors. The left-hand corridor is straight, so it's just a matter of jumping or crossing the pools; the wider pool may be a problem for those who try to jump. The right-hand corridor ends where the narrow pool ends; there's a door above the pool, which may mean some tricky negotiation. The central room has two pillars between the pools; there may actually be a chest or other object between the pillars, as a lure to timid adventurers. There's an exit on the opposite side of the narrow pool as well that leads to an irregular room.
Geomorph F14 is a large rectangular pool that almost completely fills a square room. The pool is swimmable, assuming the characters want to get wet, and assuming there's no blind cave piranhas or other creatures in the pool, and assuming the pool is water and not something more dangerous, like acid. If the characters don't want to take the risk, there's a narrow balance beam that crosses the pool. TWO narrow balance beams, actually, at different heights, since there's an east-west passage running across the square room at a slightly higher level. There's another short corridor running above another passage in the upper left quadrant that leads to an upper level chamber.
Geomorph F15 is an irregular-shaped pool in a cavern. The pool is not really an obstacle this time, but it might contain: blind cave fish or molluscs (suitable for a snack,) an aquatic monster, or a sunken treasure.
There's actually only one entrance to the cavern on the lower level. The southern portion of the cavern has a ledge, though, with exits on opposite sides. No stairs are marked, so you have to add some if the rooms mapped on either side of this geomorph are on the same level as the cavern. There's also an unconnected curved tunnel in the upper right quadrant.