Exploration acheivements
I used this page to help me with my explorer, it has a list of all the areas in game, now you just have to compare it with your maps.
http://wiki.guildwars2.com/wiki/User:Bluestone/Explorer
Hope it helps.
One thing is 100% completion, other thing is 100% exploration!
What you need is to end the exploration thing.
For that you need to “open” in the Maps all the different small zones that have a name in white letters in each map.
Some of them are quite tricky to get, so i advice you google about each map and check what zones you need.
Hope this info can be helpful in some way:)
If you have 100% map completion and are just trying to finish up exploring another easy way is to go to the wiki for each zone that you are missing. Open up all of the shiverpeak maps, and then look for areas that don’t have a POI, Vista, SP, or WP, then you can compare with your map and see if you have the areas that don’t have anything in them. Hope that helps.
For me one tricky one in shiverpeak explorer was tribulation rifts behind the tomb of morlog vista
The best way to find all those hidden places is to start doing your JP achievements.