Kiribati is generally a safe place to travel. However, it may be risky to be outside after dark in Beito or along the beach in South Tarawa, especially for single females. However, virtually all problems are caused by drunk males, not career criminals.
Don’t drink the water without boiling or filtering. Chemical treatment is not recommended as it may not prevent giardiasis. The lagoon (especially around Beito) is heavily contaminated, and may make the entire island segment smell bad at times. Always ask first before going out in the water at each location on South Tarawa — no matter how inviting it looks. This is a good idea on other islands too. Get a hepatitis A shot, and be up-to-date on all your other vaccinations, preferably several weeks beforehand. Mosquitos can be very bad at times, so use repellent. Be sure to bring your own insect repellent and sunscreen, as these are not available locally. Don’t expect any needed medications to be available either. (Some are, but you never know what is or when.)
There’s no malaria, but dengue fever outbreaks (mosquito transmitted) do sometimes occur. The fish caught locally may give you food poisoning (ciguatera), so be extra careful. Ciguatera is not preventable by cooking or freezing the fish. Promptly treat even the smallest cut, sore, or insect bite, as these can become infected very easily.
Medical evacuation insurance is highly recommended for Kiribati. Many outer islands have no airstrip, making any sort of evacuation long and difficult.