Some might call it just a wooden path or boardwalk, but I was wondering if this structure had a specific name.
As you have said yourself: boardwalk.
plural noun: boardwalks.
a wooden walkway across sand or marshy ground.
NORTH AMERICAN a promenade along a beach or waterfront, typically made of wood.
If you are happy to accept an American use then that is specifically a boardwalk.
Dictionary.com put the meaning relating to the shore first, without any sort of regional caveat:
a promenade made of wooden boards, usually along a beach or shore.
According to this article in The Family Handyman, the visible portion of a wooden walkway (the generic term for a boardwalk) is the decking. (It's normally composed of wooden slats.) The decking is supported underneath by a series of joists.
So your picture shows the boardwalk's decking, and the slats of which it is composed.