Which is the most suitable excursion in Belize for elderly person?



We are trying to decide on an excursion in Belize during our forthcoming Panama cruise on Coral Princess. We like the sound of the Jungle River Tubing but one of our party is elderly and we are wondering if this excursion would be suitable. Is it very difficult to get in and out of the tubes? He can cope with the tubes round the 'river' at Disney's Typhoon Lagoon in Orlando, where you get into the tube from the steps, but would this be more difficult and strenuous?

(It says this excursion is exclusive to Princess, hence posting this message here.)

An alternative to this would be the Baboon (Howler Monkey) Sanctuary but even that says there is a 'substantial level of activity'. Does anyone know how long or strenuous the walk is?

Can anyone advise please?