Calypso's Raft

Calypso's raft is a raft Calypso gave to Percy so he could leave Ogygia. It will take the user anywhere they wish and return after it completes the task. Only Calypso is not able to ride it (as her punishment for supporting her father in the First Olympian War, Atlas, was being stuck on the phantom island, Ogygia, forever). In some myths, it is said that is was a gift by the god Poseidon. Percy used the raft to arrive on the shores of Camp Half-Blood after staying on Ogygia for a two week period of recovery.

This is probably based off of the raft Calypso allowed Odysseus to build to leave her island. This raft is not the same however, as it was destroyed by Poseidon.