To be entirely honest, the majority of the specialties are very much things you can learn on your own. The advantage of learning them through a course is mostly just the fact that you are spending time in the water with an instructor, and getting all the tips and tricks they can share with you from their experience.

Boat diving as an example, is less about the actual act of jumping off a boat to dive, more about the ways you can pack and setup your equipment to be more comfortable, how to make sure the boat can keep track of you while you’re down and a host of other nuances that take a long time to get together but can make every difference between enjoying yourself on the ocean and going home dissapointed.

Really, anything you need you can always rent. Equipment can be expensive so it is important to know what to even look for before you ever spend the money. My general recommendation is spend some time diving before ever thinking about what to buy.

That being said, Masks are relatively cheap, will make or break a dive, and fit every person so differently that likely a rental mask will never be entirely comfortable. Investing in your own mask before certification is never a bad idea, as long as you do the research to make sure it really fits.

At its core, Technical diving is still just diving. It requires a higher degree of skill and some extra knowledge, but those things are attainable by anyone. If you are a quick learner you can always work on them by yourself, but at the end of the day you don’t know what you don’t know, and the best way to get the necessary skills and knowledge to even begin your first tech class is to spend time with an instructor focusing on just teaching you what to practice.