Much of the new content added in Phase 4 of Season of Discovery requires players to tread water, which can be a very slow task for quite a few classes. Several Runes in particular have watery components, and unless you've got someone with Water Walking or an Elixir of Water Walking nearby, there's not a lot you can do to bypass the annoyance of extra time underwater.
All Phase 4 Runes Discovered in SoD
Luckily, the Season of Discovery team had some foresight and added Water Treads.
These boots provide the user the buff Treading Water, allowing them to walk on water for 10 minutes, with a 5-minute cooldown.
These boots are available from Duke Hydraxis in Azshara at Honored with the Hydraxian Waterlords, for the low price of, so make sure to pick them up as soon as you can to ease all of your traveling needs.