While we didn't see any large packs of stray dogs, there are plenty of single dogs around. And most of them seem to exist on tourism. Overall they seemed to know how to work the tourists. So not really a danger, just a warning.
One thing the islanders take very seriously is the respect that must be shown to the ancestors. This, combined with the need for strict measures to ensure the preservation of the amazing and unique statues and structures of Rapa Nui mean that touching any of the statues or walking or sitting on the ahu - all of which are regarded as sacred to the ancestors by the islanders - is something to be avoided at all times, and by everyone.
The very nature of Easter Island, with so many sites spread over the whole island, many very isolated and unguarded, means this has to be a matter of trust - and, of course, not all visitors have the sensitivity or sense of respect that is necessary to observe this. You can be sure that if a ranger sees you standing or sitting on an ahu or touching an ahu you are in for an uncomfortable few minutes as you will be picked up on it severely. Your own sense of what is right and proper should mean you won't find yourself in that position of course.
While not always immediately apparent to visitors to Easter Island there is underlying political discontent on the island. Rapa Nui independence from Chile is a controversial topic on the island and one which casual visitors would be advised to steer clear from unless you know what you are talking about. While it probably won’t affect your stay here it is important to remember that the isalnders do consider themselves very different from mainland Chileans and are fiercely proud of their unique culture, language and traditions. Be aware of political sensitivities and don’t voice your political opinions until you are sure who you are talking to and that they are comfortable talking to you about the topic. Rapa Nui culture was fiercely suppressed by the Chilean government in the past and resentment is still evident.
While hiking along the remote north coast, you will come very close to some sheer cliff faces. Be extremely cautious along this route as crumbling cliff edges and long grass can make a stumble or trip very likely. There is little hope for anybody who falls from the edges of these cliffs with jagged rocks lurking below and strong rough seas bashing the cliff face. This is also a consideration you should bear in mind if seeking out the White Virgins Cave which is located in a cliff face and is not the easiest or safest place to locate and access. You need a good head for heights and willingness to scramble down a sheer cliff face! Not to be undertaken lightly.
At many of the sites within the National Park you will see signs warning visitors not to touch the artefacts. This may seem obvious but it is amazing to see the amount of people who think its OK to touch and even climb on top of these ancient treasures. It is not only the moai themselves which can’t to touched but the ahus on which they stand are also off limits, not just due to their fragility but also because they are considered sacred places. While exploring some of the more remote sites it is easy to get up close and personal with many of the moai statues and there aren’t always signs telling you not to touch but whether there are signs or not, it is forbidden to touch any of the artefacts regardless of their size or location.
Watch out for roaming packs of dogs in Hanga Roa. The locals just seem to let their dogs out to roam and they can be a pretty rowdy and argumentative lot.
They do not seem to bother you ( maybe if you have food) and often flake out under trees in the midday sun but they can be a bit worrying if you are not used to being around packs of dogs.
If you decide to hike or bike or in anyway travel on your own around the island, carry some water. You will find craft vendors outside a number of the sites, but none will be selling drinks. I was told that on weekends that there are some concessionaires who sell food and drink at the beach, but on the weekday morning that I visited their stands were closed and the beach empty.
The island is very rocky, so a good pair of shoes is necessary here. Whatever you do, avoid walking barefoot anywhere on the island with the exception of the two sandy beaches. The lava is sharp, especially at the coast. Also, the rocks can be slippery in spots.
The island is mostly a national park. It is also described as the largest outdoor museum in the world. The vast majority of people who do their research know what the rules are visiting Easter Island. One big one is to not walk on the ahu or touch the moai. The ahu consists of a platform in addition to a ramp leading up to it. The ramp will be marked by stones distanced equally apart. In many of the locations, signs will remind the visitor not to walk on the ahu. Not only does it cause unnecessary wear and tear to this unique place, it also is disrespectful to the culture. In the photo, it is unfortunate that this guy is teaching his son a bad habit. Note that he is on the ramp while his son is about to touch the moai. I hope that the place will be around for many more generations. In order for this to occur, everyone needs to help out.
The island is full of livestock, especially horses and cattle. They will be found in the road quite frequently. Because there are some blind curves, this could be a danger to some. It does not matter which part of the island the road is on, there are likely to be animals nearby. While Easter Island is an open air museum, it should also be considered a large ranch. For those who walk or ride mountain bikes, the animals are not aggressive and will largely ignore your passing.
A tiny speck in the middle of the ocean, Easter Island is subject to sudden changes in the weather. Given the nature of the activities it offers, and the spread out nature of the sites you will be visiting, you need to be aware of this and be prepared, especially if you're hiking.
Bright hot sunshine can change very quickly into cold, wind and rain, and an overcast morning can just as quickly turn into blazing sun. The wind can be really strong, especially when you're up on the island's high spots. Changes in the weather can be very localized.
Setting off for the whole day? make sure you carry
30+ sunblock (and use it!)
some sort of wind/rain jacket
a shirt with sleeves
and, as there are some fairly nasty creepy-crawlies out there in the long grass (Black widow spiders, scorpions and mosquitos) preferably
Heading for caves? Carry
This is perhaps the funniest warning signs I have ever come across. But seriously, a local explained it to me that more people die of getting hit in the head by a coconut then any other random death events on the island. And au contraire to the stories I had heard before coming here, there are palm trees on Easter Island. There are other trees too but the palm trees have the coconuts you need to watch out for. These trees are realitively new, due to a big replantation of trees that has been going on the last decade. Personally, I was surprised by the number of trees I saw on this island rumored to be devoid of all trees. So beware as you stroll under that beautiful palm tree by that beautiful picture perfect white sand beach by the sea. Because if you are not paying attention and in the wrong place at the wrong time, BONK, bad news for you.
These appear to be the true citizens of the island. They are mixed breed and numerous. They are very friendly, but even so they are everywhere and leave their calling cards. They will enter a hotel without thinking twice and one evening a nice pooch came through the lobby carrying a shoe that it had picked up on someone's patio. Imagine their suprise when they came out to find only one and wondering what the heck happened and why someone would only take one shoe!
We were with a tour group visiting different locations, but the degree of difficulty and/or inherent dangers were never adequately discussed prior to departure. We are in relatively good shape and have decent balance. There were others in the group (grossly overweight and elderly) who struggled and even slipped and fell on the loose volcanic soil and sands. Be careful and ask the degree of difficulty if you have any issues at all.
It is not totally safe on Easter Island as other comments suggest. We had a whole backpack taken from our room as we slept along with a daysack (which thankfully the thieves dropped). Crime is on the increase on Easter Island.