AKVALAB is an underwater mission for FIST.
The PDF is 4 pages, cleanly organized, with good, thematic illustrations.
New items and Traits are included in AKVALAB, and they add some utility and flavor, but the meat here is the mission. It centers around a Soviet marine base and a nearby sunken temple, and gives the players good opportunities for both subterfuge and firefights. It's also careful to spell out different approaches the PCs might take, and ends with a fun monster reveal and escape sequence.
Overall, AKVALAB is a solid FIST adventure and a good pick for a oneshot or campaign intro. If you're looking for some underwater spy antics, give this a shot.