Visitors from North America, the UK (and rest of the EU), Australia, and New Zealand do not need a visa for stays in Kiribati up to 30 days. A valid passport and return/onward ticket are also mandatory, and you may be asked to provide evidence of funds for your stay. Vaccinations for diphtheria and hepatitis A are recommended.
Health and Safety
Kiribati is one of the safer places in the world; certainly more so than Hawaii in the sense of crime. Busier areas, however, do have some problems, though mostly petty crime such as pick pocketing in the towns. It is best to avoid Beito and South Tarawa beaches after sundown and single females should exercise special caution by night.
While dengue fever can break out on occasion (no vaccine for this), Kiribati is malaria-free so no need for anti-malarials. Visitors should always have a quality insect repellant to hand, though, and use liberally at night.
There is just the one hospital in Kiribati, the Tungaru Central, which is located in South Tarawa. It is a basic facility and visitors will have to pay for treatment, so keep receipts for any visits. The hospital sends medicines out to dispensaries for the other atolls, which are also basic. Bring a supply of any medicines you might be on and note their generic name.
Lagoon swimming is safest, although Tarawa Lagoon should be avoided near the towns due to the pollution. Be careful when swimming or snorkeling on ocean-facing reefs. It is best to go with a tour when visiting remoter places if you intend on snorkeling or, at the least, check with locals on conditions. Tarawa roads can be tough due to cattle traffic and the free-for-all driving manner of local drivers.