Foreign visitors to Sri Lanka should ensure that their passports are valid for at least six months beyond the date of entry. All visitors are required to obtain a visa prior to arrival, which can be done online or through the Sri Lankan embassy or consulate. In terms of vaccinations, it is recommended to be up to date on routine vaccines such as measles-mumps-rubella (MMR) vaccine, diphtheria-tetanus-pertussis vaccine, varicella (chickenpox) vaccine, and polio vaccine. Additionally, Hepatitis A, Typhoid, and yellow fever vaccinations are recommended for some travelers. It's also important to stay updated on travel advisories and entry restrictions, which can change frequently.