There are a number of items you are going to need for Mermaid Diving.
Mask with Snorkel – It’s not possible to dive deeper than a few meters with swimming eye goggles as you are unable to equalise the air space but there are a number of low profile scuba marks out there to give you the comfort and reliability you need…before of course then looking at style and colours (but not unless it fits Mermaids!)
Mermaid tail and Fin – To start with you might want to use the all in one designs that pull on and off quickly but in time you may want to professionalise your tail/fin choice. There are custom made tails that you can fit over your chosen fin that will make you look splendid indeed. In fact my very own tail is designed like a lionfish and I use the Mahina fin. There are of course other fin styles. If you like mine then I have an arrangement with MermaidAvenuePH to ensure we can prioritise your order.
Standard fins or free diver fins – You are going to need these for when you act as the support Mermaid. Again there are many different designs out there. I already have mine from my scuba gear. Perhaps the best choice is one that you can put on quickly as you will need to change from tail to support fins when its time for your buddy to dive.
Surface support equipment – Basically this is a floating ring or similar design capable for holding spare weights, kit and cameras, drink bottles, hats etc, etc, etc.
Here are some examples.
Scuba Jay 