It mentioned ship explicitly in the disruption section, so by my reading a cruise is covered. Normally if it isn't there is a specific exclusion in the policy and there isn't here.

However...
“Trip” means a journey outside Your Country of Residence which must commence and end in Your Country of Residence, or a journey within Your Country of Residence which must include a flight, or at least one night of pre-booked accommodation away from home. Trip is extended to include any journey within Your Country of Residence for Car Rental Benefits (Section 1.5) only. Trips must not exceed 90 consecutive days with a maximum 240 days during each 12 month period. The Trip length will be extended to 365 consecutive days for Your Children under the age of 25 on a Gap Year

So It looks like Ex-EU trips for UK residents might not be covered.