Helmet is required to be able to go underwater, but once there the helmet can be removed. However, without it players will take 5 times 20 Drowning damage kicking in after four seconds of standing still. It is useful out of the depths, too: some monsters, like Water Elementals use drowning damage attacks.
That means you won't be able to go underwater if you not wearing it :)
Source : TibiaWiki
Question Revival V contestMarch 17, 2024
Interview with Solkrin - lead of the Customer Support team at CipSoftDecember 20, 2023
Become a TibiaQA Supporter!May 09, 2023