Fina Nagu-A Vent

Latitude: 12.867^οN Longitude: 143.819^οE  Depth: 2200 mbsl

Fina Nagu A is one of the youngest calderas in Fina Nagu volcanic complex in southern Mariana Trough. During the visit in 2016, scientists could explore two small domes inside Fina Nagu A caldera and extinct hydrothermal chimney complex about 14 meters tall (Okeanos Explorer 2016 dive summary). In addition, small patches of diffuse flow of weak hydrothermal activity (3 – 5.5 °C) was found. The extinct chimneys were good habitat for brisingid seastars, corals, gastropod (one species-Desbruyeresia). In addition, there were snails, a cusk eel (Ophidiidae, Acanthonus), a ctenophore, several predatory sea squirts (tunicates) and a deep-sea lizardfish (Bathysaurus cf. mollis). Around the diffuse flow there were dense clusters of small tubeworms. In addition to biology, there were volcaniclastics covered in thick manganese crust (Okeanos Explorer 2016 dive summary).