The Pacific Plate is the largest plate on the PB2002 map1 and lies almost entirely under the Pacific Ocean. USGS describes the circum-Pacific Ring of Fire as the place where the Pacific Plate meets many surrounding plates, and calls it the most seismically and volcanically active zone in the world.
Along the San Andreas fault zone in California, the Pacific Plate has been grinding horizontally past the North American Plate for 10 million years, at an average rate of about 5 cm per year (USGS). In the west, USGS describes the Marianas Trench as the place where the fast-moving Pacific Plate converges against the slower Philippine Plate. PB2002 draws a narrow Mariana Plate between the two along the trench. Its Challenger Deep reaches nearly 11,000 m below sea level.
Not every volcano sits on an edge. The Hawaiian Islands formed more than 3,200 km from the nearest plate boundary. J. Tuzo Wilson proposed that they formed as the Pacific Plate moved over a deep, stationary hotspot, though USGS notes that later studies question whether hotspots are fixed. The islands get younger to the southeast: the oldest rocks on Kauai are about 5.5 million years old, while the oldest exposed rocks on the Big Island are less than 0.7 million years old.
The islands are only the young end of a much longer trail. The Hawaiian Ridge-Emperor Seamounts chain runs some 6,000 km from the Big Island to the Aleutian Trench off Alaska and is made of more than 80 volcanoes (USGS). A sharp bend in the chain shows that the motion of the Pacific Plate changed abruptly about 43 million years ago, from a northerly to a more westerly direction. Loihi Seamount, an active submarine volcano about 35 km off the southern coast of the Island of Hawaii, has already risen to within 1 km of the ocean surface and may become the next island in the chain.