Cruise ships are back, visiting ports around the country bringing with them more covid.

Health NZ is refusing to say if there are Covid-19 cases on the cruise ship Celebrity Eclipse currently docked in Lyttelton.

More than 130 people onboard the Ovation of the Seas have tested positive for Covid-19, and the ship had not been following current Covid isolation guidelines.

Aerosol chemist Dr Joel Rindelaub told Charlotte Cook he was definitely not surprised.