With Patch 8.2 out there are a lot of new things to do. One vendor, a murloc in Nazjatar you have to rescue to unlock, Mrrl carries a mix of very interesting and quite useless things. One of the things he can carry is the Tidestallion mount, a very pretty reskin of the seahorse mount from Vashj'ir. In order to see the mount you need to have the Benthic cloak Azsharan Stormsurge Cloak. This allows you to see the hidden items Mrrl sells. The Tidestallion does not become available on all realms at once when it is available, so you may need to find a Tidestallion group in group finder in order to get to a shard where Mrrl has it.
One of the mechanics of Mrrl as a vendor is that you will need to run between different murloc vendors around your camp in order to purchase your way through an item chain to get the currency you need for any purchase you make. Weak Auras has a string that allows you to automatically purchase the items you need (when it works), however if you don't use Weak Auras, the Wowhead comments that help you figure out what you need for each final currency can be as clear as mud.
Fortunately there is a very nifty website available that allows you to plug in what you need for your final purchase, and gives you a concurrent step by step vendor list of who you need to talk to in what order to get as much as you can of what you need to keep the process to a minimum of fuss and flailing about. Check out https://mrrl.io/
and get those Tidestallions.