Transportation is more of a problem on the Placencia peninsula than it is on Ambergris Caye, and the distances (up to 15 miles from Riversdale to Placencia village) are much greater.
From time to time there is a van shuttle service up and down the peninsula, but I don't think it is running now. Even when it's running, it's not always running.
There are taxis, though they are surprising expensive -- up to US$15 or $20 one-way from Placencia village to the far end of Maya Beach. From Robert's Grove to Placencia village, can't recall what the taxi would be, as I always have a car, around US$5 probably.
Some places, including Robert's Grove if I recall correctly, offer bikes to guests.
By the way, my family and I stayed at Robert's Grove a couple of weeks ago. It was really terrific, especially the new "deluxe condo suites" which are fantastic. The regular rooms are only so-so. I would go for the deluxe suite or at least a junior suite. The staff is excellent, and the food at the restaurant quite good. The pool is very nice, and they are building a second pool which should be finished soon.
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