S1E5 : Undersea Volcanic Eruption! The Straw Hats in Turmoil

As the crew plumb the depths of the sea in search of Luffy, Sanji and Zoro, they encounter the terrifying and mysterious secrets of the deep, including an undersea volcano, whose eruption almost spells "the end" for the Straw Hats as they continue on their way to Fish-Man Island.