Hi dog1.
I believe the GSL forces all objects to ground level... in this case, the ocean level below the pier.
I'll see what can be done. In newer versions of FS, we have platforms, but not an option here. We also could use generic buildings with zero height, and place them at the desired elevation. Perhaps runways can assign elevation... so the pier can have an invisible runway. Area16n is too clumbsy and will raise the water level.
Dick