On Lake Berryessa, anyone who has a credit card can rent a jet ski for $60 per hour. The jet ski is theoretically capable to carry two riders simultaneously. Having never tried to ride the jet, one can assume that it is very easy. As it occurred actually, the jet is quite unstable and tends to flip over all the time, especially on slow motion. My friend Leon and I ended up in water in two seconds after we made our first attempt to saddle a jet ski together. Thanks goodness, I did not take my camera that I was going to use originally on the fly...