Can't remember the name of this book!

[nmclearn]

I read this book, oh about 20 years ago; I'd like to read it again but can't remember the title or author. It was about an older man on a cruise ship in the Mediterranean who is suddenly transported to a desert land, inhabiting the body of a much younger person, with a telepathic lion as his companion. I can't remember much more except that they were traveling across this desert (in search of something?), in the Earth's past (ie. before the Med filled up), and I think it was also a 2 or 3 book series. Can anybody help with the name or author?

[David Boultbee]

The Gandalara Cycle.

Great series. The original books were grouped into 2 trilogies (Volume 1 and 2) and a final book called The River Wall.