Yes the ferry can be really busy. To help increase availability and to help keep costs down for regular travellers there is a facebook page called 'Share a cabin on Northlink'
Also, from memory there are only about 6 dog friendly cabins on board, so get in early if you need one, or check daily for a cancellation.
Also, from memory there are only about 6 dog friendly cabins on board, so get in early if you need one, or check daily for a cancellation.