The red circles represent methane seep from the database of Skarke et al.
(2014) based on NOAA Office of Ocean Exploration and Research surveys, with updates (many additions and a few deletions) based on geophysical surveys by the U.S. Geological Survey (USGS) Gas Hydrates Project in 2016 and 2017. Labelled seeps have been surveyed during ROV or deep submergence vehicle (DSV) Alvin
dives since 2001, with most dives carried out since 2012 (compilation by C. Ruppel, pers. comm.). The yellow circles indicate the locations of seeps targeted for Deep Discoverer
dives on NOAA Ship Okeanos Explorer
Windows to the Deep 2018 expedition (EX1806).