Jane's i688 Hunter Killer.

I created a scenario with a Soviet Delta III doing a transit patrol at 10 knots. It's Heading was 180'. My heading was 90' at 10 knots! I reached the end of patrol area around 18:00 hours, the depth of the water was 17,000 feet! I had -500 points deducted for running aground!
Is it possible to leave one area for another? I thought it was all one big ocean!
Thanks!
Christopher Tarana