There are several mirelurk eggs and mirelurks in the water area. The main trapper’s shack has a mini-nuke beside the Advanced-locked explosives crate.
The shack has a red button that will activate the explosives planted in the pool area. There are at least 3-4 sets of explosives you can detonate, preferably when the mirelurks are within range. Also, if you kill all mirelurks in the area, a Queen Mirelurk will appear.
The quarry has an interior area which is accessible through a door in the pool with the mirelurk eggs, north of the wooden bridge. There are more trappers hiding inside clear the area and loot the containers and corpses. The chamber also has a cooking station, armor workbench, and weapon workbench.
In the second floor, there’s a green trunk and on the small table beside it, you can pick up an issue of Islander’s Almanac. The powered building in the western side of the quarry has a fusion generator with a fusion core and weapons workbench inside.