Swimming

By default, players cannot swim: They sink to the bottom of liquids such as water and lava, and can only jump when they reach the bottom or other block. Flippers and Neptune's Shell grant the ability to swim, while equipment that grant flight (such as Rocket Boots and Wings) also function underwater. It is possible to swim in Lava with the help of: Obsidian Skin Potions, any swimming item will do(best option is Neptune's Shell because it grants breathing), if you don't have Neptune's Shell then you can use Gills Potion to breath in Lava(or water).