This is what the border looks like:
http://www.moonglow.net/eclipse/2003nov23/ (photographs taken in November, 2003, by Fred Bruenjes)
These photographs discussed within the context of the Maurice Allais effect:
http://www.theflatearthsociety.org/forum/index.php?topic=30499.msg1629054#msg1629054There is no outer rim ice wall.
What we do have is a very dense section/barrier made up of aether, the very reason the distance earth-moon, measured with the help of radio wave signals, must be measured taking into account the fact that light will decrease its speed greatly when encountering the aether barrier.
During 1939-1945, the Nazis tried to go beyond the dome of aether using the most advanced UFOs, mercury subquark gyros, but they could not.
If a boat or plane tried to go head straight into the barrier, what would happen is this: the plane or the boat, will slowly be diverted to keep the path of direction within the space/aether under the dome, that is it will be encountering the very barrier itself, more dense as we approach the dome, and will be blocked from going beyond, but without the pilot/sailor realizing it.