Why not both?

That's actually pretty cool, though...

I've been on there! There's a diner by the mouth of the tunnel. It's cool!

They build most of it as a bridge, since it is cheaper to work on top of water than under it. The tunnel area allows for ships to pass

We have one near me. Chesapeake Bay

Sydney Harbour Bridge too

It's the James river in Norfolk, The Monitor Merrimack memorial bridge.

Check at the Øresund bridge/tunnel. It connects Copenhagen, Denmark, and Malmö, Sweden. It is a 16-kilometre bridge-tunnel-manmade island,

this is the bridge in virginia.my family lives there