The cave is part of a much larger cave system, but the rest of the area is blocked off by a hidden stone door. This door can only be opened by going through the East Empire Company Warehouse.
Enter Brinewater Grotto from the beach. Inside is a small pond and three horkers. They will become aggressive if approached too closely. There is nothing else of note in the grotto. The only way to get to the larger section of the cave is during the related quest.
(On the Lighthouse side)
- An unlocked chest outside in a niche to the right of the entrance.
(On the Trading Company side)
- An easily missed collection of potions, wine, and alto wine along the right wall scaffolding in the area with the first two enemies.
- Several chests of varying difficulty in the area around Gulum-Ei.
- An unlocked chest underwater (by the swimming bandit).
- A Dibella Statue on a shelf.
- A Markarth Guard's and a Solitude Guard's Shield, located on a shelf.
- Slaughterfish eggs at regular intervals in the water.
- A wrecked boat on the far side of the water after the dog has a barrel with various ingredients.
- Boats by the last guards before the confrontation have chests.
- An Imperial helmet can be found on the shelf to the right of Lady Dibella's statue. It resembles a hoplite helmet. (Near Gulum-Ei.)
- A Dwarven sword, a steel-war axe, and an ancient Nord sword can be found in a box on the shelves behind the nearby boss chest.
- Leveled bandits, found by entering through East Empire Company Warehouse during Scoundrel's Folly, but not from this side.
- Frostbite Spider.
There are several traps, both bear traps and tripwires.
- The bandits do not respawn and the concealed exit does not reset to the closed position, allowing the Dragonborn to enter the cave near Solitude Lighthouse and loot the entire cave once the items found inside the cave have respawned.
- On a shelf in the area where Gulum-Ei is found, there is an unusual white lily-like flower. This is very likely from the Dibella Statue. (There are 2 large Dibella statues in the preceding area and one has the flower missing.)
- Scoundrel's Folly is not able to be advanced from this side. Go to the East Empire Company Warehouse side.
- The loot/locked chests respawn.
- It is possible to enter the blocked off section of the cave by facing the stone door and pushing a wooden plate up against it and running up against the plate until one clips through the door. Once through, one can then operate the middle lever beyond the wood gate to open the stone door they just merged through to provide an exit, and also to allow any potential followers through. All loot is intact, though the bandits that occupy the place during the quest do not appear, making the three frostbite spiders and the hostile dog the only enemies within the whole cave system. However, do not approach the door to the East Empire Company Warehouse too closely. The door is key-locked (meaning it cannot be picked open) and getting too close (about 6 feet or so) will start the "Scoundrel's Folly" quest, though the quest itself is broken: there is no quest description, and as Gulum-Ei is not present anywhere, the game points the Dragonborn to the The Ragged Flagon - Cistern, which itself is not accessible if the player is not a part of the Thieves Guild. In order to exit, one has to go back the way they came.