If you'd rather not build a pit, there are lots of other options that you can secure - inflatable kiddie pools are a common favorite, but if you really want an awesome experience for your party participants - rent a bouncy castle!
We hosted a bouncy castle party three times now, and it's out of this world fun! The past two times we've mounted several 4' fluorescent UV light fixtures with dual bulbs to the outside of the castle and added 10 gallons of fluorescent lube into the mix - our banner background was shot with that system. More photos and details will be forthcoming - we need to do a better job documenting the setup process and party progression for customers in the future.