ArriveCAN is mandatory for all travellers to be allowed to travel to Canada:

All travellers must use ArriveCAN before flying to Canada. It’s simple and free. Not using the app may result in denying your boarding.

Full details in the below link:

Use ArriveCAN for a faster border experience – Canada.ca

Mandatory Vaccine for all travellers:

Effective October 30, travellers departing from Canadian airports, and travellers on VIA Rail and Rocky Mountaineer trains, will be required to be fully vaccinated in order to travel.

To allow travellers time to become fully vaccinated, there will be a short transition period where they will be able to travel if they show a valid COVID-19 molecular test within 72 hours of travel as an alternative to providing proof of full vaccination. If travellers have not already started the vaccination process, or do not start soon, they risk not qualifying for travel as of November 30.

Full details in the below link:

Mandatory COVID-19 vaccination requirements for federally regulated transportation employees and travellers – Canada.ca

All travellers aged 12 years and older must be fully vaccinated:

Effective Oct. 30, 2021: All travellers aged 12 years and older must be fully vaccinated in order to be allowed to board on Planes, Rail or Cruise ships. This applies to both International and Domestic traveling.

Details in the below link:

Mandatory COVID-19 vaccination requirements for federally regulated transportation employees and travellers – Canada.ca