If you are experienced and confident enough to go 2-3km offshore this is a must do. The normal tourist usually pays for this stunning journey, but it cannot be explained how beautiful it is take this journey with your kite. Starting from the main beach allows you to visit the popular Jonny Cay first, afterwards you can take your kite downwind along the reef over the luminescent turquoise water until an old ship wreck which hit the reef a couple years ago.
The view of the island from this distance is a view most tourists won't get as part of their trip. In addition, you can go further downwind to visit el Acuario and stop afterwards in the mangroves next to the harbour which is in short distance to Chamey's nautica. If you want to stop here you won't be charged the $10.000 COP fee just for landing, but I recommend to continue to go further south past Rocky Cay, after which unprotected of the outer reef you will be able to ride in the waves.
I personally used to stop around San Luis (but you can easily go further south), self-land the kite, pack up, and hitch a free ride with one of the golf carts back to el Centro.