I assume you are talking about brushless. if so the Chinese will tell you they work both ways (forward/reverse) and this is true. Just reverse any two of the three connectors and the motor will change direction. Not much use if the model is in the middle of the lake!
You can buy ESC's for brushless that will reverse under control from the transmitter and they are usually marketed as suitable for model boats. ESC's suitable for cars replace the reverse function with a brake, although there are some that can be configured to either brake or reverse.
If you are running a fast electric boat you may not want a reverse but I suspect this will only be suitable for waters with no weeds or obstructions and all round access.
GiantShark (ex GiantCod) offer a very competitive range and clearly identify the functions available. You may need to buy additional electronic boxes to select the functions, although you can use the built in functions by listening to beeps from the ESC.
I think it is safe to say that if reverse is not mentioned, then its not present.