I really hope that submarine archaeology improves quickly. I bet there's all kinds of real "lost" civilizations lurking under the water, which will change some entrenched ideas about human history. It would really be something to find out that some previously dismissed myth turned out to be more or less true.
To be honest, I wouldn't hold my breath. I'm sure submarine archaeology will find interesting evidence of past ship wrecks in the Indian Ocean, Southeast Asia, and the Mediterranean. However, massive continental changes happen on time scales of millions of years. The current continental arrangement has been more or less the same since human civilization began to develop.
Human civilization started to develop after the end of the last Ice Age. Over the past 5,000-8,000 years coastlines have not changed substantially (but they likely will this century due to anthropogenic climate change).
Without a doubt. As I stated above, the Mediterranean Sea and Indian Ocean are probably littered with old ship wrecks.