During Christmas, I want to travel to the ABC islands (Aruba, Bonaire, and Curaçao). I know I can only fly between the islands, but how can I travel on the islands? Is it difficult to rent a car? Is there (good/affordable) public transport?
It will not be a problem to rent a car on either of the islands, although for Curacao I found the warning that it is advised to book and reserve before you arrive as the stock is not huge and rental locations do run out of cars fairly regularly. I guess that in popular times it will be the same on the other islands.
All three islands have buses and taxis but no trains. Aruba also has trams.
Tourists are not known to use buses but can do so. It is still the norm to pay cash, on popular routes and during day time they can run as often as every 15 minutes, on less popular routes usually once an hour or more often. But check the time tables. On Curacao there are also minibuses, which are more flexible but also more expensive. Bonaire has tuktuks locally called Bon Tuk, electric ones, which are also available for tours.
Taxis are regulated, with fixed prices for set distances or locations or open to negotiations with the driver and agree for the price before you get in. Meters are not used.
So you see, renting a car is the norm but without you can get around as well.