Get Vrekt

I found that the easiest way is to take the Flight Path to Hafr Fjall.
Then ride down the side of the cliff to the area with the PvP Watch Tower (sometimes a PvP World Quest area).

Just shortly before you reach the Watch Tower, head East and continue down to the water. From here, it's a quick and straight run/swim to the quest area which lies just at the beach as the map indicates.

It of course helps to have water walking or a Water Strider.

This is a real pain to get to without the ability to walk on water, or without running through PVP (with or without mount barding). Probably the easiest way is to use a Goblin Glider Kit (GGK), or perhaps Rocfeather Skyhorn Kite, from Hafr Fjall flight point (FP). The kite will last long enough (1 minute flight at time of writing), which should easily let you land on a small rock island neck to the dock in target area.

If you don't have the Hafr Fjall flightpath, it is also possible to take a goblin glider kit from the top of Thorim's Peak, flying around a badly behaved obstructive mountain in the process, either picking up the missing FP on the way or just flying straight to the WQ. Speak to Vethir at Lorna's Watch (A) or Cullen's Post (H) to get a ride to Thorim's Peak.