When Achelos Diving Helmet is worn, Conduit Power II and Dolphin's Grace I is applied to the player. Both effects are immediately removed if the helmet is taken off.
If the player wears Achelos Diving Helmet and dedicates the other Armor slots to the same pieces of another Armor set, then the player will gain that Armor's full set bonus- along with the helmet effect. However, doing so will only grant the player 3/4 of the Armor set's cumulative per piece effect. E.G. Wearing Ghoulish Armor, but having Achelos Diving Helmet in the helmet slot will still benefit the player with both Ghoulish's full set effect and Achelos Diving Helmet's effect, but Blaster damage will only be increased up to 30%- instead of 40%.
Achelos Diving Helmet will also provide its own oxygen, meaning that it will prevent the player from drowning, along with preventing the player from taking damage in dimensions with unsafe atmospheres- such as Vox Ponds and Lunalus.
Achelos Diving Helmet can be obtained as a drop from the following mobs: