Sea Touch ElixirItem 5+
AlchemicalConsumableElixirPolymorph
Source Core Rulebook pg. 549 2.0
Usage held in 1 hand; Bulk L
Activate 
Interact
This briny concoction alters the skin on your hands and feet. The spaces between your fingers and toes become webbed, granting you a swim Speed of 20 feet for the listed duration.

Sea Touch Elixir (Lesser)
Item 5Source Core Rulebook pg. 549 2.0Price 22 gp
The duration is 10 minutes.
Sea Touch Elixir (Moderate)Item 12
Source Core Rulebook pg. 549 2.0Price 300 gp
The duration is 1 hour, and you can breathe underwater.
Sea Touch Elixir (Greater)Item 15
Source Core Rulebook pg. 549 2.0Price 920 gp
The duration is 24 hours, and you can breathe underwater.