Open-Air Bus or Taxi Tour with Infant?

[renchow]

We will be travelling with an infant (11 month old) and two grandparents (60s healthy and mobile) - so a group of five. Which is the better way to do an island tour - taking the open-air buses at the end of the pier (as recommended on other posts) or hiring a taxi (recommended by others)?

 

For the open-air bus, would it be possible or advisable to a car seat - are there seat belts for it? can we leave it on the bus while we get off? do we even get back on the same bus, or is this a hop-on-hop-off type tour?

 

For the taxi, if we were to spend an hour or two at a beach, would it be safe to leave car seat with driver? has anyone tried this?

 

Thanks in advance!!