The Department for Transport has issued strict rules on the number of guests allowed on UK domestic cruises this summer.
It has capped numbers at 1,000 guests or 50% of capacity, whichever is lower.
This is valid from 17 May, when cruises are permitted to begin, until 21 June.
All guests must be UK residents.
The first ship scheduled to set sail is MSC Virtuosa, which has a capacity of almost 5,000 so will only be able to sail at about 20% capacity.
There is no government mandate that guest are vaccinated although several line have made it compulsory such as P&O Cruises and Virgin Voyages.
The DfT also imposed a ban on groups of more than six people or two households socially mixing indoors.
From June 21, it hopes to remove all social distancing limits on cruise ships, meaning cruises could potentionally operate at full capacity.
