Twenty years ago when I first had my pond dug I wanted to build a "viewing room" alongside the pond. My ex wife thought I was nuts so I didn't do it but I had the engineering done and it was pretty easy to have built. The structure was an 8 foot diameter reinforced concrete sewer preform with a 24" opening on one side. A brass ships port hole was to be the window and the bottom was a solid concrete disc made to seal off the bottom. The seams were to be tarred for water proofing and the top of the thing would sit about 1 foot above water level and extend down 9 feet. The top could be decked over and a gazebo built and a spiral staircase would lead to the "viewing room" Long story short I listened to my ex and don't have the viewing room now! PS she found another reason to prove I was crazy and divorced me anyway! :rolleyes:

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