The Ocean Potion is a consumable item that will stop the drowning meter from increasing and increases your swimming speed by 50% for 5 minutes. It was added to the game on 2020-03-23 with the New Wave update.
Ocean Potions can be crafted in your Crafting Menu (to be opened by pressing "q" as the default key), but only after the according crafting recipe has been unlocked.
The crafting recipe for the Ocean Potion can be unlocked in your Crafting Menu by:
To craft 2 Ocean Potions, you'll need:
Use this potion by putting a (stack of) Ocean Potion(s) into any quickslot, then selecting this slot and clicking your right mouse button. Alternatively you can drag a (stack of) Ocean Potion(s) from the inventory over your character's portrait on the right side.
Using an Ocean Potion will stop the drowning meter from increasing, although it will not remove it, and increases your swimming speed by 50%. The effect lasts for 5 minutes. Consuming another Ocean Potion while the previous one is still in effect will reset the timer to 5 minutes. There is a small cooldown after consuming this potion to prevent accidentally consuming multiple potions at the same time.