You pay after you are done.

After a one hour minimal charge, you only pay for the portion of the additional hour/s or minutes you use. As an example, if you kayak for one hour and ten minutes, you only pay for one hour and ten minutes - not two hours.

This way you can decide how long you want to kayak while you are out, and you don’t have to rush back to beat the clock and not get charged for the next full hour.