Arenas?

How do i get to:

-The Dedrimore Arena (the arena near Droknars Forge)
-The Crag (the arena near Ember Light Camp)
-The Amnoon Arena (the arena near Amnoon Oasis)
-Fort Koga (the arena near Henge of Denravi)

Go to the Battle Isles (click on ship south of LA on map) and join in either CA or TA. Those arenas are part of the normal map rotation.

I take it you've got the Prima Guide. Well unfortunately a lot of the information in that guide has changed over time. The Arena's you have on your map/guide are located on the Battle Isles as mentioned above. They can be accessed by clicking on the boat just below Lion's Arch and "Traveling" to the Great Temple of Balthazar. The Random Arena's, Team Arena's and Hero's Ascent (which replaced theTomb of the Primeval Kings) can be accessed from there.

In fact, he doesn't have to have the Prima Guide. All of the maps found on the Internet are outdated as of the Factions PVP Weekend event. Even the in-game map is kinda outdated - you can clearly see the portal leading to the Amnoon Arena in the game map even though it is not accessible.

To further clarify and sum up: All the arenas except Ascalon and Shiverpeaks have been removed from the Tyria map and equivalents are now in the Battle Isles.

Good point, still this question seems to come up more with owners of the guide rather than the folks who get the maps off the internet. We seem to accept that info on the internet may have stuff that's wrong in it. If it's printed it must be right. And we all know that the Prima Guide had stuff in it that was out of date before the game was even released. It was based on Beta info after all.