forgive me, i'm extremely sorry but i Must allow the itching urge to do an Actually and correct -- no, no, you don't get Surf on the ship, you get Cut which you need to progress the game, and then the ship leaves, and you only get Surf much later. BUT! if you traded from a friend a pokémon that knew Cut! you could just keep going without ever letting the ship go! and come back when you could use Surf! And in the version of the rumour I knew, you needed Strength to push the truck.
and i actually did all that as a kid, and it didn't do anything :( you can't even interact with the truck.
and I still told myself that I must have messed up something, and there really was a Mew under there, I just couldn't get it.
I did meet Missingno. tho, but iirc I couldn't catch it.
Anyway, deep apologies for the fact-nitpicking, and thank you so much for provoking it, for sharing and reawakening these thoughs and feelings and knowledge I never think about :') What a sweet, yearning nostalgic moment. I miss the gaming magazines you would write to to ask for help when stuck with a level...