No, "higher than..."
You'd never use "highest than ... "
In the sentence
In long, narrow bays, tides are higher /highest than in other places.
Higher flows smoother but are we comparing more than 2 places so pick highest?
3 answers
What about this one?
Storms in the North Sea are worse/worst in the winter than at any other time.
Storms in the North Sea are worse/worst in the winter than at any other time.
worse
Higher and worse are both comparatives and are used with than.
Higher and worse are both comparatives and are used with than.
1 answer