Fireproof Lava Boat
From the Super Mario Wiki
The Fireproof Lava Boat (also known as the Fire Proof Boat) is a small, inflatable and apparently heat- and lava-proof raft owned by King Koopa.
In The Super Mario Bros. Super Show! episode "Too Hot to Handle", King Koopa, after capturing Princess Toadstool, has his Shy Guy minions begin the inflation of the Fireproof Lava Boat, which King Koopa plans to leave the island of Waki-Waki with, with bellows.
After being told by Fryguy that Mario and Luigi have clogged his Lava Machine, which begins to back-up and spew lava everywhere, King Koopa flees to the raft with Princess Toadstool to escape the lava machine before it destroyed him. Seeing King Koopa approaching, Mario, who had hid himself in the raft with Luigi, throws the Fireproof Lava Boat's life preserver in King Koopa's path; getting his foot caught in this life preserver, King Koopa is tripped by Mario, who pulls the rope attached to the preserver. Once he trips, King Koopa relinquishes his grasp on Princess Toadstool, who is sent sailing through the air, only to land in Luigi's arms in the raft.
After the lava machine explodes and sent lava everywhere, Mario, Luigi, Princess Toadstool and Toad, who Mario brought aboard the raft with the life preserver, use the raft to ride a wave of lava out of the volcano they are in. It is unknown what they did with the raft after they were flung with it out of the volcano on to the beach of Waki-Waki.