From Pathfinder Treasure Vault (Remastered), which isn't enabled.

Submersible Helmet (Greater)

ITEM 13

Price 2700 gp

Usage worn headwear

Bulk L

A greater submersible helmet is a streamlined sallet with a visor and a flanged rear. While wearing the helmet with the visor down, you can see, hear, and speak clearly underwater. You also have a +2 item bonus to Athletics checks to Swim.

Activate (concentrate, manipulate)

Frequency once per day

Effect You can breathe underwater for 8 hours. During this time, you have a swim Speed equal to your land Speed.

Pathfinder Treasure Vault (Remastered)ORC