If you want to catch Marlin, the Cabo area has mostly Striped Marlin. There are also some Blue Marlin, which are generally much larger.  There are also Black Marlin in the Cabo area, but they more rare are found further off shore. 

Scout out where the best fishing is: They will all tell you if they are catching fish or not, and what kind they are catching.  But, what they may not tell you is that the fishing may be better in one of these other areas twenty or thirty miles away.  You'll need to scout that out for yourself, or take your chances.  

When is the best time?  It's not unusual to catch a marlin at almost any time you go out, at various times of the year.  It seems that March is the time when the southern tip of Baja has the poorest Marlin catch rate.  While at that same time, further up the Sea of Cortez, or maybe out of San Lucas, but over on the Pacific Ocean side, it is possible that these locations are doing very well with Marlin.

Other Fish:  That said, Marlin is only one fish, and there are many, many kinds of fish in the Baja area.  Dorado is the best tasting, from my book.  Other fish, Yellow Tail, Rooster Fish, Yellow Fin Tuna, Wahoo, Sierra, Amberjack, many varieties of Snapper, Jack Crevalle, to name a few are prolific in the Cabo region.  Even on off days for other game fish, if you are want to troll for Sierra not far off shore, you'll probably catch some.  Sierra is  a very game fish related to the Mackerel family.  You will find it to be really good white mean, few bones, and best (I think) barbequed.  For Fish Tacos, any day of the week, any of these fish are great.  Cabo is said to be the world's most productive salt water sports fishing area.  Because the warm waters of the Sea of Cortez mix with the cooler Pacific Coastal waters, and there are underwater mountain ranges just off shore, it's great for fish life, and great for fishing.

From the Gringo Gazette, Sept. 15, 2008

Where to get a fishing charter: 

La Playita, my first choice for average, non Marlin fishing.  You'll find two charter groups here.  One is called Gordo Banks Fishing Charter, and the other is La Playita Fishing Charters. To get there you have drive into San Jose, take the dirt road, soon to be a paved road, over the large estuary arroyo east of the town of San Jose.   Follow the signs to La Playita.

La Playa Sport Fishing: is operated by Tomas Cantor.  Tomas can be reached from the U.S. at 011-52-624-148-0469, or locally at 044-624-148-0469.  Tomas can arrange for your fishing via an open bowed, no restrooms on board, Panga or a Marlin Cruiser, depending upon what kind of fish you are searching for.   

Gordo Banks Fishing:  Owned and operated by Eric Brictson at 011-52-624-142-1147 or locally at 044-624-142-1147.  Let me know if any of these numbers no longer work.  I've never used them, but have heard all good things about their operation.

Palmilla Fishing Fleet:  Used them a couple of times.  No complaints.  Caught fish. They're located at the beach by The Palmilla Hotel, now called The One and Only Palmilla, about two miles west towards Cabo San Lucas.

You can also contract through the Palmilla Fishing Fleet, by talking to the fisherman at the Palmilla beach area.  Carlos Navarro is currently the manager of the Navarro Sportfishing Fleet, and can be reached at 011-52-624-119-14-30 from the US, and 044-624-119-1430 in Cabo.  Not my first choice. 

Bait: What is important, is to ask if the bait fish are in.  If the bait fisherman can't get bait fish, sardines, then they have to use lures, which are generally not as good at catching game fish.  For Marlin, they often go out and spend the first hour or so using bait fish to catch larger bait fish, such as mackerel or Bonita.  If you are fishing for Marlin and they are only using a lure, it's my feeling that your odds are reduced, but, you may still catch them.

Catch and Release:  It's recommended these days to release Marlin, as their populations and average size has declined over the years.  Seeing them alive, up close and personal is very spectacular, as they are a beautiful and colorful wild animal, and after you snap your photo, it's a great feeling to let them go.  No taxidermist has ever really replicated that real wild and alive look in all their efforts to paint the fiberglass replications of them. More often than not, your wife will make you hang it on the wall in the garage anyway.  And, if it's meat you want, there are other fish that taste better, and one Marlin is too much fish for one family anyway.  When released they can be caught again, and can have normal lives making baby Marlins.  That's just my perspective.   If you want to keep them, that's your call.  

You will need to let your boat's captain know if you want to keep or kill your Marlins before you go out.  I've heard stories about fish getting released or clubbed to death by mistake, so you'll want to make your wishes known before the boat hand kills the fish, or in case you did want to keep it, you want him to know  before they let it go.  There's often a language barrier unless you speak fluent Spanish, so bring the subject up early on.  

You need to bring your own food and drink, and if you can, the Capitan and his deck hand are generally very appreciative if you bring enough for them.

Here's a good link to a website that has a lot of fishing information: Click Here.

Below, as you can see, Surf Fishing is popular along the beach in front of the condo, known as Costa Azul, meaning the Blue Coast.  In the one bedroom condo we have three surf casting rods and some gear available for you to play with.  Don't worry about breaking the fishing gear.  It's there for our guests to play with.

Below is a huge 90 pound Tuna caught by our amigos, Jaime and Edmundo ("Mundo").  Like many do, they split the catch of the day, regardless who was responsible for actually cranking the reel that brought the fish in.  They look different, but these are actually photos of the same fish.

Sometimes, though you think you are fishing for Tuna or Dorado, you may instead catch a Striped Marlin: