Using bracer of Armor to apply the "Of the Deep" template of the "Plate armor of the deep" magic item.

This would mean the wearer can breathe underwater and can converse with any water-breathing creature with a language.

CONSTRUCTION REQUIREMENTS

Feats Craft Magic Arms and Armor; Spells freedom of movement, tongues, water breathing; Cost 13,150 gp

Not sure of final costs, but for +1 fullplate it was 24,650 gp

Sadly, this item is outside the scope of the books we allow, so it isn't possible.

For breathing under water, I would recommend the Helm of Underwater Action, Pearl of the Sirines or Bottle of Air, or a potion of water breathing, all of which are from the Core Rulebook. We also allow you to play an Aventi who are able to breathe under water.

Potion of Water Breathing - 750gp

Bottle of Air - 7250gp

Helm of Underwater Action - 24,000

Pearl of the Sirenes - 15,300

Trust me, it's cheaper to play an aventi :)

don't forget the Cloak of the Manta Ray 7,200gp