Here you can find info on the game's optional Sea Races.
You unlock Sea Races after beating Main Mission #25 (Hood Safari, where you escape via jet skis...). There are four Sea Races in the game and you can do them in any order you wish (although we have them in the game's order below).
Each race will take place on jet skis. If you don't have one you can find an empty one at the race that you can use, so no worries! Most of these races are pretty straightforward but we do have some tips!
Racing Tips:
Know where you are heading: like other races, as you approach a checkpoint it will have an arrow in it pointing to the next checkpoint, letting you know where the next checkpoint is. This is especially helpful in the Sea Races as you can cut through the water much faster than on land. As you race look at the arrow and where the next checkpoint is, and then prepare to cut the water as you hit the checkpoint so you are lined up with the next one that much faster.
About Waves: You may not always be battling waves as you race, but if you do keep in mind that waves will make you airborne and unable to turn. If you hit them head on you'll jump further. This is OK as long as you don't need to turn, but if you do cut into the wave in the direction you need to go so that you don't lose precious time.
If you need to make a sharp turn and you find yourself going to fast, try letting off the gas for a second while you re-adjust yourself (again, the jet ski's turn is fantastic). You can re-accelerate quickly with the jet ski's, so simply letting off the gas can take care of many of your sharp turning needs.
Sea Race #1 - East Coast
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This one is pretty easy and quick. It won't take you more than 2 minutes overall (we clocked around 1:20 actually). The race starts off with a fairly straight line and turns into a figure eight throughout the race.
As you start get ready to cut to the right after the second checkpoint. This one act will likely put you in first place. After that you'll soon be making a hard right turn so be ready for it around checkpoint 5. After a few more checkpoints (around checkpoint 9) you'll be taking a hard left turn as well. This leads into a clock-wise circle around the small island to the north, so get ready for all the right turns you'll face and keep the acceleration down until you finish.
Sea Race #2 - North East Coast
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This race takes place near the Gordo Lighthouse, which has a bunch of rocks nearby but we will be racing around the islands to the south. This race also hase about 10 more checkpoints than the last one, so it is slightly longer.
To start you won't have any tight turns, so expect the AI to keep up with you for longer than the last race. By cutting the checkpoint corners you can get rid of them by checkpoint 5-6. Keep hitting checkpoints as you stay on the right of the rocks and around checkpoint 15 you'll cut to the left and start heading back up. As you pass the a big island around checkpoint 20-21, get ready for a sharp left turn. You'll turn back to the right at checkpoint 24, then sharply to the left at checkpoint 27, so watch out for those sharp turns and you'll be ok.
Sea Race #3 - Raton Canyon
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Now this is a fun race. You'll be racing down the canyon, which has plenty of rapids and is fairly narrow. Also, you'll only have four people in this race instead of eight (probably due to how narrow this is).
There are a few tight turns (mostly in the beginning) and of course there is the occasional rock hazard, but if you stay in the middle of the river and let go of the gas on any sharp turn you'll do OK. The rapids you encounter will make you jump slightly, but far less than a normal ocean wave. Enjoy this race as it is truly one of the best ones in the game.
Sea Race #4 - Los Santos
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Another fairly fun race. This race will have you whizzing by dock and pier supports, so be careful! Once you start get ready to cut left after checkpoint 2 and you should find yourself out in first place in no time. Past checkpoint 2 you are going to make a big clockwise circle and then head back into the pier section. Crashing is your biggest danger here, but you should be able to react in enough time to avoid any stationary support obstacles I trust!
Blaze ahead and get ready for a small counter-clockwise semi-circle at around checkpoint 17, then continue on and be ready for one last sharp turn to the right leading to the finish line.