Where can one still sail on cruise ships without being vaccinated, with the least possible differences of treatment on board?

After those challenging years, cruise lines restart their voyages. Most apply vaccine requirements or give a different set of rules to Covid-unvaccinated travelers.

In which conditions can an unvaccinated traveller sail as of today and take part into as many activities as possible, with the least rule differenciations in comparison to a fully vaccinated passenger?

It depends on each cruise line. Furthermore, each line can apply different rules in different parts of the world, surely influenced by local laws such as the recent Bahamas decision. The whole picture is difficult to track.

MSC, for instance, only require a test for boarding as an alternative to the vaccine, in Europe. Everyone gets the nose swab at the terminal. Once on board, there used to be a excursions-only rule to go ashore during port calls. Recently, this rule was relaxed for fully vaccinated travelers, which is the only form of different treatment applied. The whole ship is equally accessible without consideration for anyone's vaccination status.

I heard that other lines such as NCL apply "no jab no sail"; Royal Caribbean adds extra charges and restricts access from some parts of the ship.

Note: this is a practical question. To keep the answers constructive, I do not think this place the appropriate one to debate about pros & cons of the vaccine, personal responsibility, conspiracy theories, judgments about the desire to travel without vaccine... Those topics can lead to heated discussions.

Let's keep it focused on practical aspects for someone who has chosen not to vaccinate for multiple possible reasons that are out of the scope of the question, and cannot fall into officially sanctioned "medical exceptions". For instance, it would be OK to say "cruise line X lets you on board but you cannot access half of the restaurants".

Note : edited to tone down some words.