you have mastered ocean warfare. After taking this feat, you gain the following benefits:

-you gain proficiency with a trident, net and spear, if you do not already have it. 

-you gain advantage with weapon attacks whilst submerged in water

-as a bonus action, you can summon a trident to your hand, with it seemingly appearing in your hand out of pure water. this weapon counts as magical, but otherwise functions as a standard  trident. once summoned, the trident can be dismissed as an object interaction.