Diving on Hydrothermal Vents at The East Pacific Rise This expedition to hydrothermal vents on the East Pacific Rise (EPR) consists of a 27-day research cruise on board the R/V Atlantis, mother ship of the United States’ only deep-diving manned submersible, called ALVIN. We depart Puntarenas, Costa Rica, on 26 November and return there on 22 December 2002. In the interim, I and the other 20+ scientists on board have 17 ALVIN dive days funded by the National Science Foundation (NSF) to further our biological investigations.