We took a train from Atami to Izu Kitagawa. We didn't buy a ticket specifically, so I don't know if it counts as a sea-viewing train. One side of the seat faces the sea, and the back can hold large luggage. The other side has a single row of seats. We only went to Kitagawa. There were not many sea views along the way, but they would appear suddenly. It was like a brightening, vast sea and sky. The train went through many tunnels. Maybe there are more coastal scenery from Kitagawa to Shimoda. The overall feeling is pretty good. We also encountered the black ship on the way and passed by:)