The Raft is a craftable Boat in the Shipwrecked DLC. It requires 4 Bamboo and 3 Vines to craft and is found in the Nautical Tab, it is always available to craft. It has a durability of 150, which will deplete over time or if damaged. It can be repaired with the Boat Repair Kit.
Occasionally, abandoned Rafts will be found floating in Shallow Ocean biomes, accompanied by 2 Spearguns.