I cannot recommend this adventure enough. On a trip filled with amazing experiences, like snorkeling and scuba diving, this is the first thing I tell people about when talking about our trip.
I'm going to keep this short, sweet, and spoiler free.
Sloughing is amazing, we scoped this experience because of the kayaking, but agree that the slough stole the show.
Garl is an incredible guide, and photographer.
You can rent insect gear (we used just the pants for sloughing), Garl will let you know whether or not it's been really buggy, and if he recommends the full set. You should definitely bring water shoes.
The full day is a just that. A. Full. Day. but incredible and so utterly worth it.
We packed a sack lunch, but there is a stop at a campsite/boat dock where you can buy food. You will need to eat during the full day experience.
He will tailor the experience to what he thinks the members of the group can do. My wife, myself, and another guest were all young and fairly fit, so we kayaked pretty far, and definitely felt it the day after. That said, he'll keep in mind who's with him and how far to go. Like I said, Garl is an incredible guide.
You will get wet, but we didn't find a need for our spare clothes. (Bug pants for the slough, athletic clothes for the kayaking).
Go on this adventure. Seriously, it was simply incredible. The wildlife, the flora, the sunset, all of it was so utterly unique to anything I've done before. This is especially true for people like myself who might thing "This sounds kind of neat but..." should stop at that "but", and go see the Everglades with Garl.