Advanced Aquatics (4e Feat)
From D&D Wiki
Advanced Aquatics [Rakshia]
You gain webbing between your fingers in addition to gills and an even more hydrodynamic shell, allowing you to move through water with the greatest of ease.
Benefit: you gain a swim speed equal to your own speed, may now breath underwater, and you ignore rough terrain penalties from moving through any liquid. In addition you ignore the penalty to climb on slick surfaces.