It's best to rent a car to maximize your time on this trip. Taxis and public transportation are available, but they may be more time-consuming and expensive. Car rental costs around $40-60 per day, and travel time between the locations is around 15-20 minutes.
If you have more time, you can visit some of the other attractions in Bermuda such as Horseshoe Bay Beach, Crystal Caves, or St. George's Historical District. If you have less time, you can skip Cooper's Island and spend more time at other locations. Don't forget to bring sunscreen, snacks, and comfortable shoes for the hike.