OK, I think I have this issue sorted out.
In the WaterLurker's properties, under the Entity Tab, you will find: PlayerDetectionHeight.
Set this Value to any number at or above the height of your water level in relation to the starting height of the Lurker. For example if the water is 1.5 unit deep, make the PlayerDetectionHeight = 1.5
Then when you stand on any feature that is above that height, ol' Sploshy will ignore you.
Still testing to see if this is correct... Any verification would be appreciated...
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...ummm. Now I gotta learn how to add the Script Entity and write the script so he starts as inactive and then starts coming after you once you are halfway across his pond.
This scripting stuff does NOT come natural to me so any advice would be greatly appreciated.
Thank you...