Q. What is it supposed to be on the show? A. It's not completely clear. It's a ramshackle place on the water where Dexter docks his boat. It includes a fuel dock, a cluttered market, and a dingy restroom. Q. Where is it supposed to be on the show? A. It appears to be a re-creation of (or tribute to) the very real Jimbo's, in the Florida Keys. Q. When did we see it on the show? A. In Episode 1, of Season 5, "My Bad". Following Rita's murder, Dexter is experiencing an emotional crisis, and at one point decides to just run away from it all. He gets in his boat, the Slice of Life, and heads out to sea. In this scene, we see him pull up to a dock, fuel up his boat, and then walk through a rather dilapidated structure, before entering a cluttered, funky market (or cafe, it's hard to tell). Inside the otherwise empty store, he observes a bearded guy yelling, demanding to know where the key to the restroom is. The guy behaves like a real jerk. Finally, the guy bends over the store's counter and finds the key for himself.  He turns, and sees Dexter watching him, then becomes even more obnoxious & insulting. As the guy heads into the restroom, Dexter's old instincts kick in, and he almost unconsciously follows him. When the guy sees him again, in the restroom, he becomes hostile, asking what Dexter's problem is. Dexter mumbles that his wife just died, and that it's his fault. The jerk then makes an obscene comment about Dexter's dead wife (Rita). That is a mistake. Dexter, who has been holding it in, snaps. He beats the guy to death with a boat anchor, savagely smashing his head over and over, long after he's dead. After Dexter's rage subsides, Harry appears and comments that it was the first human thing he's seen Dexter do since Rita died. He tells Dexter it's OK to show his emotions. Dexter drops to his knees in anguish and screams in grief & rage, finally letting it out...

Q. What is it actually in real life?

A. A mashup. (See my speculation below.)

Q. Where can I find it in real life?

A. I'm not precisely sure exactly how they put this scene together, but I'll share my conjecture with you.

The first thing to realize is that they were apparently attempting to re-create an actual place in Florida, where they filmed a scene for the first season (when they were still actually filming in Florida). The scene was the one where Dexter and Debra are eating at an outdoor picnic table, under a shelter similar to the top photo on this page.  They are talking about the (yet unnamed) Ice Truck Killer, and Dexter helps Debra realize that the Killer must be driving a stolen refrigerated truck.

Here's my page about that first season scene. It contains map links to the location.

The name of the place, in real life, is Jimbo's.

It's a funky, colorful, one-of-a-kind, rather ratty collection of spray-painted buildings, junk cars, and a dock, located off the Rickenbacker Causeway, on Virginia Key (one of the Florida Keys).

Considered a local landmark, of sorts, Jimbo's offers shrimp, smoked fish, bait, beer, bocce ball, a laid-back style, and a very unique location in the semi-tropics.  The place has its own website, at jimbosplace.com.
And you can see more photos of the Jimbo's via Google Images. You can also watch a short video about the place here.


As you can see, it greatly resembles the waterside location where Dexter encounters the jerk in the restroom.

Pay particular attention to these two photos below, from this website:


  

Look familiar?

It should. Compare it to this screencap from the episode "My Bad".



Look closely, now, and notice what is written in pale aqua paint on the side of that fake lean-to...

So, we know that they were attempting to re-create a place like Jimbo's. The question is, how did they do it?

The scene is clearly a mashup of various elements.

At the start, when Dexter is out on his boat, they recycled the old boating scenes from season one, the ones seen in the pilot episode. That was actually shot in Florida, not far from Jimbo's, in fact.

Then it looks like they mixed in some additional footage of the Florida area (possibly left over from the pilot episode), by adding a little green-screen CGI to insert that Miami shrubbery into the background of some new boat scenes.

Then they cut to a physical re-creation of that ramshackle spot somewhere here in SoCal, when we see Dexter walk from his boat to the market.

But that's where the reasonable certainty stops, and the questions begin: Is the opening establishing shot of Jimbo's (the top photo of an iron girder frame shelter, with graffiti on it) an actual shot of the original Jimbo's in Florida, or part of the local re-creation? My guess would be that it's the original, but I can't find a perfectly-matching photo online to confirm it.

According to the actor playing the jerk (Brad Carter), all of his scenes were shot on a sound stage at the studio.  Which tells us that the market and restroom scenes were all shot at Sunset-Gower.

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

A.  Since I did pages in previous years about both Jimbo's and those Florida boating scenes, it wasn't particularly hard to recognize that the dilapidated set was supposed to be Jimbo's, and that the boating footage was obviously re-used from the first season.

The Brad Carter inside info came from a YouTube video interview he gave about the show.  (Thanks to Rick for tipping me to that Youtube video.)