My teenage boys want to kayak. Any suggestions that won't cost a fortune.
Also the forcast is for rain every day--what is there to do when it rains. I am in a panic. A week inside a costly resort with three boys and nothing to do!!!

Usually when the forecast says rain, it rains for for just a short time. If you are staying at a resort, they probably have kayaking, and if it's AI, it may be included (non-motorized sports usually are).

You can visit Tulum ruins on a cloudy/rainy day. You can take the Collectivo (public van) or rent a car for the day. Either would be cheaper than an organized tour.

It's still plenty HOT even when it rains. Just continue doing whatever you were planning on. I love being at the beach or in the hotel pool in a rain shower (as long as there's not thunder & lightening). You get wet, you dry off. It's no big deal.

You could also go to Coba when you are doing Tulum.As MFNYC says it rarely rains all day and is generally very warm when it does.

We were in the Yucatan at the beginning of July and had quite a few days with nonstop rain- very unlike most years. Not to be discouraging but just so you can plan for it and e thrilled when it doesn't happen.
Strange weather everywhere this summer!