An independent Alberta is guaranteed sea access under UNCLOS Articles 124 to 125.
Claimed by: Commonly stated by Alberta independence advocates
False: False as written according to the settled evidence. How we rate.
Summary
The UN Convention on the Law of the Sea does give landlocked states a right of transit to the sea, and it even mentions pipelines. But the same articles make the terms of that transit subject to agreement with the transit state, and they affirm the transit state's full sovereignty over its territory, so the treaty would not compel British Columbia or Canada to build or permit pipelines. Who is actually bound matters too. Canada is a party to UNCLOS, having ratified it in 2003, but the United States, the other obvious route to tidewater, has never ratified the Convention and is not bound by it, and a newly independent Alberta would not automatically be a party either and would have to accede. Either way, real-world access would come down to negotiation, not an automatic treaty guarantee.
Evidence
UNCLOS Part X gives landlocked states freedom of transit, but Article 125 says the terms must be agreed with transit states, and Article 125(3) preserves the transit state's full sovereignty over its territory.
Canada ratified UNCLOS on November 7, 2003 and is a party to the Convention, but its transit provisions still require agreement with transit states.
The United States signed but has never ratified UNCLOS and is not a party, so a transit route to tidewater through the US would not be governed by the treaty at all.
Legal experts describe the claim of a guaranteed pipeline route through B.C. as misleading, because access still has to be negotiated with the neighbouring country.