Drysuit
From WikiRaider
This is one of the unlockable outfits in Tomb Raider Underworld. Screens have shown her wearing it in the Artic Underworld. Lara mainly uses this in colder waters. It consists of a a one piece black rubbery suit with blue strips going down Lara's arms and around her neck.
Xbox 360 Content
Another outfit ,other than the Blue Wetsuit, a red and black version of the Dry Wetsuit will be available on the Xbox Live Market.