I believe the unvaccinated will have to provide proof. See insurance requirements below.
Unvaccinated guests 12 and Older: Guests who are 12 and older and do not have or are unable to provide vaccination documentation will be considered unvaccinated and will have additional testing at their own expense and must follow health and safety protocols described below, including:
o Negative results from a pre-arrival PCR test for COVID-19
o A PCR test at the terminal
o Antigen testing onboard the day before debarkation
o Travel insurance requirements
o Shore excursions required to visit ports
o Additional health protocols onboard
Insurance Requirement As a condition of boarding, each unvaccinated guest 12 and older departing from a Florida homeport on a Royal Caribbean International cruise must provide proof of a valid insurance policy that has a minimum of (a) $25,000 per person in medical expense coverage and (b) $50,000 coverage for emergency medical evacuation and no COVID-19 exclusions. The insurance policy must name the unvaccinated guest as the policy holder or beneficiary and may be purchased from a travel insurance company of the guest's choosing or through the Royal Caribbean Travel Protection Program which fulfills these requirements and provides other benefits for travel protection. Insurance is required for sailings from August 1 through December 31, 2021 (except for bookings made between March 19, 2021 and June 28, 2021).