Random Path AI

General
1

I want to have a random path AI or if easier one that runs from one waypoint to another, what the easiest way?

2

Could you elaborate?

3

Walk randomly around the ground layer for terrestrial creatures, and swim around in the water layer for fish, or if simple just repeat a group of waypoints, a->b->c and repeat.

4

simple => easier

5

Sorry for the delay.
You can try the RandomPath (http://arongranberg.com/astar/docs/class_pathfinding_1_1_random_path.php)
It will give you a random path from the current position.

There is an example scene called Path Types which shows the behaviour of this path.
It only exists in the pro version though. Do you have the pro version?