I've tried a few times over the years.
I had 2 books I remember vividly, The Whales Song is one of them and the 2nd was the same kind of book, large pages and illustrations.
What I remember:
There was a girl, possibly 2 children who are by the sea.
They go out at night and the tide is pulled right back and it reveals a lost city.
There may be a seashell involved in calling her to the city (though very vague on that)
She goes and explores the city but the tide starts to come back in and if she gets trapped she will be there forever?
There may have been people that were turned to statues?
I remember the horror of her trying to outrun the sea
I'm sure it's a kids books with big pictures though.
This has bugged me for about 25 YEARS!
Does anyone have any idea what I am on about?