The material below is Open Game Content from a 3PP Source
Plate Armor of the Deep
Aura moderate abjuration; CL 11th
Slot armor; Price 24,650 gp; Weight 50 lbs.
This +1 full plate is decorated with a wave and fish motif. Although the armor remains as heavy and bulky as normal full plate, the wearer of plate armor of the deep is treated as unarmored for purposes of Swim checks. The wearer can breathe underwater and can converse with any water-breathing creature with a language.
Requirements Craft Magic Arms and Armor, freedom of movement, tongues, water breathing; Cost 13,150 gp