US citizens do not need a visa to enter Guam. For other nationalities, the visa requirements are similar to those on the mainland US: all travelers except those who are citizens of countries in the US Visa Waiver Program need visas. Residents of Belgium, Austria, Australia, the Netherlands, Luxembourg, Denmark, Germany, the UK, Spain, Portugal, France, Ireland, Sweden, and Slovenia may stay for a maximum of 90 days, visa-free and 45 days for Australians. More information about traveling to Guam can be found at the US Department of State website.
Health and Safety
Travelers are advised to have health insurance when visiting Guam to avoid high medical costs. Guam Memorial Hospital is the main civilian hospital on the island, but there are several private clinics and facilities for US military personnel.
Water in Guam is relatively safe to drink because it is chlorinated, and local meat, seafood, poultry, dairy products, vegetables, and fruits are fine to consume. However, you should be aware of bio-intoxication risks from cooked or raw shellfish and fish. Other possible health risks in Guam include tuberculosis and hepatitis B, so shots may be necessary. Those who are coming from a country plagued by yellow fever should have a yellow fever vaccination certification with them.
Be careful when driving, especially during the rainy season, as roads become slippery and in some cases, flood. The violent crime rate is low in Guam, but thefts are quite common, so don't leave any valuables in your car.