A cross between Red Rover and classic tag, this game is bound to become a neighborhood favorite.
Make sure your ocean isn't too wide. To determine the right width, have everyone hold hands and spread out across the field. Indicate the two sidelines with clothing or other markers. Since the game tends to produce fast Octopuses (meaning the slower, smaller kids rarely get a chance to be "It"), consider teaming a little kid with a faster player to create a two-person Octopus.
Set up a rectangular "ocean," as described in the Tips section below, and mark the boundaries.
The Fish line up at one end; the Queen (or King) Octopus stands in the middle and cries out, "I am the Octopus, queen of all motion. Let's see if you can cross my ocean."
The Fish try to run or sneak across the ocean as the Octopus tries to tag them. If tagged, they become Seaweed. Keeping one foot planted, Seaweed try to reach out and tag the Fish running by, thus turning those players into Seaweed as well.
Once the Fish reach the other side, the Octopus and Seaweed say the chant and the crossing contest starts again. The game continues until all the Fish become Seaweed. The last Fish tagged becomes the new Octopus.