Also known as "Over the Deep Blue Sea". There are plenty of ways to match actions to this song, I tend to play a pretty simplified version for younger kids. Older kids can march down to the sea, climb the ladder to the ship and salute the captain.
This song lets little kids practice actions (forward, backward, sideways, up and down) and we progress through different types of weather (sunny, cloudy, windy, rainy) until we pass through a storm and arrive back to calm waters.
It's great for any age and kids always request it. Sometimes we'll finish singing it and they'll ask to repeat the whole song from the start!

LYRICS:
It was a sunny day when I went to play down by the sea
I climbed aboard a pirate ship and the Captain said to me:
"We're going this way, that way, forward, backward
Up and down, up and down, over the deep blue sea".