The Seiko Prospex SPB439 Save the Ocean Limited Edition is a beautiful watch that keeps pulling me back for the same reason: the dial never stops changing. Seiko built the model as a 1,500-piece limited edition in the Prospex line, using its 42mm 1968 diver re-interpretation case with a 12.9mm thickness, 48.6mm lug-to-lug, sapphire crystal,…