Cook Islands tourist visa is not required for citizens of United Kingdom for a stay up to 31 days.
All travelers will need a passport valid for at least 90 days following your departure date from Cook Islands. However, we strongly recommend traveling with 6 months validity on your passport at all times. Citizens of United Kingdom can refer to www.ips.gov.uk for forms and instructions for new passport applications and British passport renewals.
Most destinations, including Cook Islands, require that you have adequate un-used pages in your passport, allowing for any necessary stamps upon arrival and departure. We recommend that you have at least two free pages in Visas section of your passport before any international travel. British citizens can get extra passport pages added to their passports at www.ips.gov.uk.
Check with your airline in case you have connecting flights overseas as part of your journey to Cook Islands. It may be the case that countries you pass through en route to your destination may require a separate transit visa. Please refer to visa requirements of the specific country.
Visitors who want to join a tourist boat, yacht or other sea-going vessel to travel beyond the Cook Islands must apply for permission to enter via the Ministry of Foreign Affairs and Immigration (MFAI).
Make sure you check the expiry date on your passport before you travel, it has to be valid for a minimum of 6 months after your departure date.