The changes affect three of the line’s ships – Seabourn Ovation, Seabourn Encore and Seabourn Quest.
Sailings onboard Ovation have been cancelled through to 3 January (back from 20 December) and onboard Encore through to 6 January (back from 25 November).
Operations onboard Seabourn Quest, meanwhile, have been paused until 10 May 2021.
The move comes in addition to an earlier pause announced for Seabourn Sojourn through to 24 May 2021.
Elsewhere, Seabourn’s new ultra-luxury expedition ship, Seabourn Venture, is now scheduled for delivery on 1 December 2021 following Covid-related delays at the T Mariotti shipyard.
Seabourn is currently finalising Venture’s revised inaugural season, and expects to announce further details in October.
A wait list is open for guests interested in Venture’s December 2021 to April 2022 sailings; the ship will debut with a series of Norwegian voyages offering chances to see the Northern Lights.
Guests booked on Venture’s inaugural voyage will be offered the opportunity to sail on a new inaugural itinerary on a priority basis before the sailing goes on sale to the public.
More details will be available to agents in mid-October.
Seabourn Quest will now operate the line’s 2021/22 Antarctica experience, meaning its Panama Canal voyages scheduled for 7 November to 19 December 2021 have been cancelled.
The line is also assessing the resumption of Seabourn Odyssey’s operations in the Caribbean; guests booked on Odyssey sailings in December are now not required to make their final payment until 60 days prior to departure.
“Our utmost priority is the health, safety and wellbeing of our guests, crew and the people in destinations," said Seabourn president Josh Leibowitz.
"We recognise the long lead time for planning an ultra-luxury Seabourn experience and with that in mind, we proactively announce the cancellation of these additional voyages.
"We are working very closely with science and medical advisors, as well as our source and destination markets, to develop protocols for the ultimate return to operations.”