As of July 3, the Atlantic Provinces will be in a Bubble. That means if you are from Nova Scotia, PEI, NB or NFLD, you can travel between provinces without isolating for 14 days.
(Update July 7) Visitors coming into Nova Scotia from outside the Atlantic Canadian bubble, will be required to fill out a tracking and self-declaration form
(Update July 24) Online version here
Those “non-bubble” visitors must provide an address where they will be staying and self-isolating for 14 days along with a phone number where they can be reached 24/7. Provincial staff will contact those visitors every day to make sure they are observing the 14-day self-isolation requirement.

If visitors who are supposed to be self-isolating do not answer their phone after 3 attempts in one day, police will be called and in-person checks will be conducted. The fine for violating the Health Protection Order is $1,000 for a first offence.
If you are going to Prince Edward Island will need to complete a self-declaration form

Click here for links to the Newfoundland & New Brunswick Government pages.