Cardboard regattas are races held on calm and shallow bodies of water. Contestants have the opportunity to build their own cardboard vessels, making it particularly suitable for groups with a focus on engineering or other technical disciplines.
Each of the teams gets a pile of cardboard, some packing tape and a paddle. No other materials are allowed to build the boats for the race, though you can opt to provide knives and scissors if you wish to make the construction of the sea-faring craft a little easier.
The event will work best if there's a time limit for the construction of the vessels. Once you've launched and tested the ships, you can give out several prizes: for most creative design, race winner and longest time afloat, for example.
As well as charging an entry fee for each of the teams participating you might also want to offer a concession stand too that sells refreshments to the participants and bystanders.
A gambling booth taking bets on the winners (with a cut for the house) is another idea (if local laws permit it). You should bear team safety in mind as well — keep a rescue boat and life jackets at the ready.
