We do get some sponsorship from different organizations.
Ok, quit some are related to players (like family or so) but others have absolutely nothing to do with underwaterhockey.
Some advice that I can give you, is by looking for companies that can give you something they don't have to pay money for. Airline companies or car rental companies.
From other companies you can, for example get something you can later on raffle or sell.

The most important thing is to present them a good sponsorship deal where you explain your objectives and, most importantly, their benefit. Uwh has a huge media potential if you play it right, and they can communicate it to their customers. It shows their company is very innovative and special.
As our sport is considered to be a weird, intense sport, it reflects this upon their company image.

Of course, also the care afterwards is important. Give you sponsors a full report on what happened. Give them one of the T-shirts you had made that includes their logo and give them a picture of the team.
Don't forget them at Christmas. Even sending a card will already make them happy.