A dry Swimming Gala in the Scutt
Sort Cubs into groups by age; Explain that the hall is in fact a swimming pool and that the Cubs have to 'swim' four lengths in Breast-Stroke, Front Crawl, Butterfly and Back Stroke. Each age group can have a go at this, with Heats Semi-Finals, Finals if numbers allow.
Then explain that the 'pool' is in Australia and that the 'pool' now contains Bull Sharks, Salties etc. The Leaders can act as these dangerous creatures, swimmers now have to escape being eaten as well as swim fast.
Alternatively the pool can be in Africa (Hippos and Crocodiles) in the Arctic (Polar Bears). South America (piranha) etc