Recently kayaking, but also boating and water sports in general. Nice to have a place with plenty of space to get changed, your own toilet, being able to wash your hands or your face and dry yourself with your own towel. Cold drinks always available as well as the ability to prepare a meal. Without bringing the CV arguments again, in these times the Cali proved exceptionally useful. Extreme versatile vehicle.
Of course perfect if you want to wake up early up in the mountains to capture stunning sunrises or wild animals if photography is your hobby.
With the bike rack permanent on, cycling adds to the likely hobbies. Or visiting cities and town as you would in a car, but not having to worry about tourist-trap restaurant or cafes.
I think it's perfect for any hobby honestly. It just provides you the convenience, the facility, the base camp from which you can enjoy any hobby. Except perhaps Stamp collecting.