Waddler is a friendly NPC found in several places. He mainly serves as a place where players can drop off items, that they can then pick up when they encounter Waddler later. he can first be encountered in Olmec's Lair. Here, Waddler appears in a cave on the very right of the first layer, just below the ladder. The player can find the exact square he is located, because it will always be either a pushable block, or a grassy tile. He later appears in the Ice Caves, just above the entrance to the caves where the Yeti King and Queen can be found. Finally, he appears in the Sunken City, with a visible entrance to his room, but only if the player had stored an item with him in one of his previous appearances.[Needs Research]
Waddler's cave in both Olmec's Lair, and the Ice Caves includes two squares that the player can place items on. When they later find them, the items they had previously stored will be located there. This is near-vital to get to the Cosmic Ocean, as it allows the player to place Hou Yi's Bow for safekeeping, but can also be used to store their Jetpack, Vlad's Cape, other back items, or weapons like shotguns in Olmec's Lair so you can retrieve it in 5-1 after Duat or after using Excalibur in Abzu. In a Tide Pool run you can take off your Back Item if it is explosive before going under the lava and pick it back up after your revived to avoid using Waddler.