Everyone forms into two teams. Half the team will be submarines the other half are harbour guards. The guards all line up with their legs spread, they are all blindfolded. Make sure they can"t peek down their noses! Each of the submarines must take it in turn to sneak into the harbour, they do this by trying to crawl under the spread legs of the harbour guards. If a guard thinks a submarine is trying to sneak through they touch down with their hand. If the guard is correct the submarine is out, otherwise the guard is out. The submarine team gets a point for each submarine they get through. When a submaine gets through, they go back and wait for another turn. This is repeated until all the submarines or all the guards are out. The teams then swap. The team with the most points wins.
Source: From the original site.(Submitted by: Alan)