Traveling to playa del carmen...how much money should we bring?

We are traveling with 2 toddlers (I'm crazy I know haha)...so there is 4 of us. We want to do an atv excursion together without the kids (who will be watched by their grandparents) and my husband is going on a beginners scuba dive with his brother. We are staying at an all inclusive, the sandos caracol, and need to know what amount of money would be appropriate!