This zone has alot of Dynamic Events, 6 or more, and they're all within 20 to 80 seconds walking range of eachother.
This is the middle of the zone. If no quest is in range, go northeast a bit and in the beach there. Each quest gives around 5.5k exp, takes like 2-8 mins for each event. The Dynamic events are pretty much always up, since they are many and have fast timers.
Also there's alot of stuff to gather as you walk between the Dynamic Events, which give ALOT of exp.
How to get to Sparkfly Fen:
(entrance at the tooltip)
Check the World Map for Sea of Sorrows, it's directly to the right (east) of where "Sea of Sorrows" is typed on the map.