MSD can have fish ID, boat diver, nitrox, Dive against debris, and underwater photographer from an intructor that teaches to the standards.
Fish ID can be extremely difficult and rewarding, and often leads to regular fish surveying (species and abundance) for REEF.org and having your survey data including in the global survey database that is now up to over a quarter-million surveys over almost three decades. Although some clearly feel that the only specialties worthwhile are those that improve your personal diving, others prefer to learn about and contribute to the ocean's health and understanding.
Boat Diver used to be a nothing course. It was revised in 2008 and is now potentially very useful to anyone not familiar with boats, such as inveterate quarry and shore divers. If nothing else, it is obvious from the way far too many people dive from dive boats that they
need the training that is in the Boat Diver course, so as to keep their gear neatly together and tucked away under the bench and not spread out all over the deck where it is a hazard to other divers.
Nitrox does not require any dives for the specialty, because there are no in-water skills Never the less, it really is an essential specialty these days for most divers, to mitigate the negative aspects of nitrogen in their breathing gas.
Dive Against Debris is an odd-ball. PADI was resistant for many years to this being an easily available specialty aimed at surveys of trash in the ocean, but consumer demand really brought it to the fore. It started in 2014 as a Distinctive Specialty; in 2016 the dive of the course became an allowable Adventure Dive for AOW; in 2018 it became available to freedivers; and in 2021 it became available to 10-year olds. It is another class that does not aim at improving one's personal diving skills but rather at one's contributions to ocean conservation through use of use's diving skills.
Underwater Photography is deemed by many to be a trivial course; the u/w photos many people take -- and how they take them -- suggest they might benefit significantly from a little instruction, and a little help with exposure, focus, lighting, color, composition, subject matter, buoyancy control, and situational awareness. Many find UW photography a compelling reason to dive; it where they get their diving joy. They want to take pictures that someone would like to look at twice, they want to do so without harming the environment or irritating their dive buddy, and they want to contribute to showing as aspect of the ocean that so many have never seen.
Too many divers on SB are focussed only on self-improvement of their own diving skills. Others wish to use their skills for exploration, surveys, pictures, conservation, things outside and in additiona to their own personal skill-improvement.
