Green Seamount is also home to a small number of hydrothermal vents near its caldera wall, which Alvin observed (on Red Seamount) to be oxide-rich with temperatures of 13.5 °C (56 °F),[4] very low temperatures for a hydrothermal vent.

[4] The expedition also noted sulfur mounds near the caldera and pit crater walls;[4] these are unusual because, unlike most mid-ocean ridge seamounts, Green's "sulfur chimneys" contain a high amount of silicon, iron, copper, and quartz, but are poor in zinc.

The only fauna observed at its hydrothermal sites were single-celled, fan-shaped xenophyophores, and some shrimp.

[4] The xenophyophores in particular were of a type that was found on many of the seamounts in the eastern Pacific region.

[7] Alvin took two samples, a sponge of the Hexactinellid family and barnacles of the Sessilia order, back to the surface for analysis.