yes cash indeed. you will be expected to tip the boat folks that take you out to the parasailing boat and the crew there as well. we just gave the tips to Elvis for him to give to himself and the crews.
Everyone likes cash in Jamaica, make sure to talk with just one person about the price and time. I made the mistake of talking to the guy on the beach drumming up business and talking to the guys in the boat that hang out by the swimming lanes. Two different prices is what i got and not a very happy boat captain. The experience was great though.