A. The Atlantic Ocean (or Biscayne Bay).

Q. Where is it supposed to be on the show?

A. Off the coast of Miami, Florida.

Q. When did we see it on the show?

A. In Episode 7 (of Season 4), "Slack Tide".

Dexter signs up Rita's son Cody with the "Young Sailors" Club, unaware that he would
have to be personally involved in their outings. But he soon finds out that he's expected to participate in a weekend boating/camping trip.

We then see Cody (and the other kids in the Club) out with Dexter aboard his boat, the Slice of Life, enjoying a speedy cruise over the waves, before they eventually dock for a camping outing.

Q. What is it actually in real life?

A. The Pacific Ocean, over 2,000 miles from Miami.

Q. Where can I find it in real life?

A. These boating scenes were shot off the coast of Long Beach, CA.

The buildings seen in the background are located between Ocean Blvd and the beach, primarily between 8th Place & 14th Place.

That's roughly between Orange Avenue and Cherry Avenue. (The numbered "Place" streets are very short streets that only lead from Ocean Blvd to the beach.)





The photos below show the matching street names/locations on the L.B. shoreline.

(and the location of Bluff Park, Dexter & Rita's new house is located in the
Bluff Park neighborhood, just one street inland from Ocean Blvd.)








(The location of the dock is examined in the page about the camping trip.
)


Here is an aerial photo, with the streets marked. And here is a map link.

Q. How the heck did you figure out where it was?

A.  This was easy. They do most of their filming in Long Beach.  So it was just a matter of looking at Bing's Birds-Eye photos of the coast until I matched the buildings seen in background of the boating scenes.