Rano Raraku is one of the top "do not miss" sites on Rapa Nui, because it is the area where the rock was mined to make the Moai, and they were carved. The trail is well kept and you can get very close to the Moai, which are strewn all over the hillside as if the carvers/quarriers decided to have a labor strike and just walked off the job one day. It is unbelievable how big the Moai are that were in process of being carved. At a certain point, you can see clearly down to Ahu Tongariki which makes for a fantastic photograph. You can also walk up to the crater (there is a slightly steeper, shorter way and a slightly longer, more gradual way but each is only 5-10 minutes). The inside of the crater is very different from Orongo and we actually saw a few guides swim in the lake. There were also horses inside, as well as Moai that were carved on the inside of the crater (how the Rapanui were going to get those Moai out of the crater and to a location we'll never really know). The ticket booth has some great photographs from earlier archeological expeditions, and there is a food area and souvenir shop. The bathrooms are clean but cost 500 pesos.
While we were on the quarry side, it rained (first light, then fairly hard). We walked down to the ticket booth and waited under the tree until the rain stopped, and then contemplated whether we should walk to the crater like we had planned. We did, and are glad we did; the ground dried very quickly and while there was some mud it was very avoidable.
And like other sites in Rapa Nui, there were wild horses in the parking lot so be alert! This is also a location that gets a ton of tourism so you need to time your visit. We didn't use a guide (we read a lot in advance and brought some books on ipad); some of the guides that we overheard were not that knowledgeable, and other people were actually asking us questions, so beware.
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