arangol.. thats just half of the map..
one important thing you got to have in mind is,
dont move the points that join with the other half, this is very important they must be in their place to be able to join back again without screwing the map up.
another thing is you should read the last 3 or 4 pages of posts alot of important stuff you missed..
take this as reference:
http://hydlaa.com/smf/index.php?topic=23402.msg257610#msg257610 and read posts from there on.
edit: by the way distance between points is around 10m that widen place you wanted is actually under water

edit2:

1: this needs to be smother and fix some of its mass its curved and lines crossing
2: in blue: this is what i changed, note this is not a waterfall

3: green is river water, here is a waterfall.
lowest point in sea bottom is at -200 meters
water level at +30m, (i should had changed this before)
just some info
