Almost 70% of heat is lost through the head. The xerotherm hat, which is warm even when wet, is ideal pre and post dive thermal protection.

The Xerotherm is the ultimate base layer for use under a drysuit. Made using Polartec® Powerstretch® which was originally developed for NASA, the Xerotherm traps a layer of air - a much better insulator than water - next to the skin, keeping the wearer drier and more comfortable. 

Designed to be worn under a padded undersuit or on its own under a crushed neoprene drysuit, it provides astonishing warmth without contributing to bulk.