Cenote and kids?

[ugagal07]

We will be in Cozumel in December.  We have done the beaches and would love to take the kids to a cenote.  DD will be almost 5 and DS almost 7.  Yes, that's young but they've already done 'strenuous' excursions and would love this.  They can also swim.  Are there any tour companies that will take my 4 year old?  Secret River will, but not Carnival's version.  Leaving her on the boat isn't an option.  They are too light to zipline and too small to ride ATVs, this was the only 'exciting' day I could come up with.  Suggestions?