You could also use the Duval Loop. It operates every 15 minutes from noon and it is free to use.
key west is made for walking
There are bicycles and scooters to rent as well. Pretty close to port. The trolley is not bad. There is also a train/car, both take you on a loop around Duvall ST.
Go to key west in the winter when its a bit cooler
Cab. However, keep in mind that cruise days can be busy, so plan on a delay on any method of transit that dosn't involve your feet.
trolley is not bad but you can Uber get used to walking just what you have to do in key west
Trolley but it was a great walk thru town. It was hot in there. Loved visiting the Hemmingway home so much more.
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