The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million km2 (40 million sq mi), it is the largest tectonic plate.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/places/techtonic-plates/pacific-plate/wikipedia/en.wikipedia.org.md
In 1881 the Corwin carried a scientific detachment including John Muir, Irving C. Rosse, M.D., and Edward W. Nelson, and in the course of the search for the Jeannette landed parties on Herald and Wrangel Islands in the Chukchi Sea.