How'd i miss this dock feature?

It's one of the sections you craft for the Beach Hideaway.

You can get the beach hideaway in Springfield Heights store for about 40 donuts. It's a part of the items that come with the beach house.

If I would have known you can place that stage on the boardwalk I would have done it years ago.
And yes that bridge is from that Beach Hideaway that they took from us. They made it a strict "5 only" and then it vanished from the game forever. And I mean literally because even with a hack you can't get anymore of the hideaway. When it first appeared you could but then it disappeared from existence like EA banished it or something.

The hideaway is still in the store in my side town. I just bought one last week.

Edit: Just went to confirm. Pic below was taken a few minutes ago. Still there