It is the very first dungeon that the player and their partner go to. The first time the player and partner go to Beach Cave Pit, they fight a Koffing and a Zubat, who have stolen the Relic Fragment from the partner. During this first visit, it is only possible to carry one item at a time, because the exploration team has not yet obtained the Treasure Bag.
It is the only dungeon that can be reached in two different ways—the first being the normal way by taking the east entrance from Treasure Town's crossroads, and the second being an entrance on the beach itself.
This dungeon is very small, and each floor will have 4-6 rooms. Missions for this dungeon will usually have E rank. Missions with client joining team or capturing outlaw will usually have D rank.