Bluebridge has joined Interislander in cancelling passenger sailings for today and Thursday due to bad weather.
A strong southerly with large swells are predicted to hit the Cook Strait throughout the next two days.
Bluebridge said as demand for sailing across the Cook Strait were exceptionally high, there was almost no available space on other sailings over the coming weeks.
It says for those not wanting to travel at a later date a full refund will be provided.
All customers affected by the cancellations will be contacted by email or text, it said.
Bluebridge said it planned to resume sailing Thursday evening at 8.30pm from Wellington and Friday morning at 2.30am from Picton, but warned that further cancellations could occur if the weather remains severe longer than forecast.
It said if further cancellations occurred customers would be notified at the earliest possible opportunity.
Interislander had cancelled sailings from Wellington and Picton through to Thursday afternoon.
Passengers could rebook or have fares refunded.
It confirmed that everyone booked to travel on Kaitaki over Easter weekend would travel on either Aratere or Kaiarahi.
A gearbox issue has taken the Kaitaki out of action for most of March, and the company said fixing it was taking longer than expected.