I remember reading a book where people figured out time travel and when they entered "Time" they could swim through it, but it would cause ripples and change things.
They would take certain time zones and physical locations as their new currency, eventually there were wars in the ocean of time.
After a while there was a hardening of the ocean of time.
I also remember that they never went to the beginning for fear of erasing Humans completely.
Characters: No main Characters
Type: A narrative history (Sci-Fi)
I read this book probably close to 12 years ago (2003?)
What book is this?