My husband and I did the walk to the summit in just over an hour and found it quite tough, especially as we got closer to the top. Make sure you have good shoes, as it can be quite slippery in parts, especially if it has recently rained (which it had the night before we went). The views from the top make the walk well worth it, we got some great photos of the city skyline. On the way back down we went through the lava caves which was really cool. It is a very interesting place, and so rewarding when you get to the top.
I wish there were a few more info boards on the island, and also that there were more ferries throughout the day, as we would've liked to stay about an hour longer, but there were only 2 ferries off the island, and if we didn't get the first, the next one was 3 hours later, which we felt would've been too long on the island.
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