Seiko Watch Prospex Sumo Chrono SSC759J1. For true watchmakers, adventure sports, whether on the sea, on land or in the sky, present the greatest challenges of all. Since Seiko made its first diving watch in 1965, Seiko has been exceeding the expectations of those whose sports require watches with truly professional specifications. Now, Seiko Prospex brings together all Seikos sports watch expertise in one collection.