Last minute activity suggestions?

My friend and I (both 23) will be visiting later in March for our spring break. As for our interests, I’m a chef and they’re a conservationist, we’re both really interested in nature and wildlife and generally cool things to see.

We’re spending 6 days, 3 in San Ignacio, 3 in Caye Caulker.

We arrive around 1pm at BZE on a Sunday, assuming not much to do in San Ignacio once we get there (we were thinking bus, but how much would a taxi/shuttle cost?)

We’ll be staying at Parrot’s Nest Lodge and plan to do some exploring in that area.

- Monday: nothing booked yet, but likely Xunantunich (without a guide?), AJAW chocolate tour, and green iguana project.

- Tuesday: ATM cave tour booked

- Wednesday: plan to leave early morning, taxi back to Belize City for water taxi to Caye Caulker, hope to stop at Belize City zoo on the way, rest of day nothing booked yet

- Thursday: full day snorkel trip with Salt Life Eco tours

- Friday: nothing booked, beach day?, maybe another snorkel or even scuba tour if we enjoy the first one so much?

- Saturday morning: head back to airport for flight back

Are there any big hits we’re missing or things we can squeeze in in the evenings? Any recommendations are greatly appreciated :)

I was also wondering would we need to book taxis and water taxi in advance, and what the shuttle costs tend to be?

Thank you!