The 水上漂药水 is a 增益药水 which grants the 水上漂 增益 when consumed. The buff allows players to walk on 水 and 熔岩. The player can sink in the liquid by pressing down. This lasts for 5 minutes, but can be cancelled at any time by right-clicking the icon.
Despite the description, players are also able to walk on lava without damage and without the need for the 黑曜石皮药水. This makes it a viable alternative to Obsidian Skin Potions when traversing the 地狱, as the ingredients required are generally safer to obtain (though more time-consuming to gather in bulk). Players should still take care when dropping long distances onto 熔岩, as they may find themselves partially submerged and take damage from the 熔岩.