Nowadays it is becoming rarer to see these marine animals. In some areas, the population does seem to be increasing which is fantastic but still not as many as there was at the turn of the last century. Several companies offer whale snorkelling tours combined with reef diving, like in Tonga or areas where they will be like Minke Whales, on the Great Barrier Reef, Australia. Most destinations will not allow scuba diving close to whales, for your safety.
With so many seasons here you can search for the destination to see them!