What's interesting about these islands is the remarkable difference between their "inner face" (the side overlooking Chile) and the "outer face" (the side overlooking Easter Island and the Pacific). While the first is quite green and full of endemic plants, the outer side is just dunes due to the wind. From the top of the mountains you can see the difference.
There are some local sailors that go around the island and show it. Ask them. They're always willing to help tourists.
The Cumberland Bay, on the Robinson Crusoe Island is where the 500 persons live. It's a group of houses with friendly people and one hotel. Nothing extraordinary, but it's an island where you can really rest, since there's nothing much to see on it
Be sure to visit where the german ship Dresden shipwrecked. And look for the canyon holes in the rock.
The islands have incredible clear waters. It's good for scuba diving. There's one place where you can rent the equipment on the island and it's right next to the pier.
If you're going to scuba dive, be sure to swim with the sea lions, endemic to this place. And you've got to spot a lobster. It's full of them!!!
Lobster are a real plague at Robinson Crusoe Islands. They are everywhere and it's in every dish. Although there aren't many restaurant, next to the pier you can have very good lobster "empanadas", a very typical chilean food. They're great, and you've got to try it.
Some guide books tell you that the only way to get to the Islands is to fly but that isn’t strictly true, there is a small supply vessel sailing out of Valparaíso which accepts passengers and will get you there in around three days depending on the weather.
However, the boat is far from practical and is really for those who want the experience of the sea crossing rather than those who mainly want to visit to the Islands.
It isn't a pleasure craft, it can be rough and it sails infrequently so you might have to wait around a month for a boat to take you back but perhaps more of a problem for the tourist is that even if you managed to book a crossing, you would (understandably) have to give your place up if it was needed by a local.
The plane can be unpredictable but when it runs it will get you there in around three hours (plus a boat trip of an hour from the airport).
I didn't actually take any tour, since I knew someone from the navy and a navy ship took us there, but there are lots of tours that go the island by plane. It's a 2 1/2 hour trip from Santiago, if I'm not mistaken.
Check out the website.
OK. Here's one thing we did and it was the most useful tip someone ever gave me.
Since these islands are far away, food and liquors are quite expensive. Trading is one thing that's always going to help.
We brought a box of 12 pisco bottles (chilean liquor) to the island. A pisco bottle on the mainland can cost not more than 2000 chilean pesos. On the island, it can go well over the 4000 pesos. So what we traded. As the old days, we traded one bottle of pisco for a whole lobster. We came back home with 12 huge lobster, costing us around US$2 each.