Location: you need to talk to Mary Ann, who is getting prepared for the triathlon in the North-western part of the map. More precisely it is close to the town of Paleto Bay (the above screenshot).
The course of this mission is not too ordinary, because it is a triathlon. The best moment to start this mission is only after you develop Franklin's stamina, although it is not necessary. Start off by jumping into water and swimming across the bay to reach the shore that you can see in the distance. Note - do not exaggerate with excessive physical strain because, after you deplete all the stamina you have, Franklin's health will start to drop. Fortunately, if you play your cards well, this is not going to happen.
The second part to the triathlon is a mountain bike race. You do not need to wait for Mary Ann so, hop onto the bike straight away and start reaching the successive checkpoints. During this trial, you should especially watch out in the spot shown in the above screenshot, where you are going to perform a long jump. Reaching the other side requires you to ride with high velocity so, if you do not want to risk a colliding with the bridges supports, you can aim your bike to the left of it and, as a result lose not too much time while returning to the main route.
The third, last, part of the triathlon is the rum. Again, I remind you not to exaggerate with pressing the sprint button and focus on keeping considerable advantage over Mary ann. The mission will be complete after you are the first one to reach the finishing line.
Rewards for the completion of the mission:
- New contact on Franklin's contacts list: Mary Ann
Requirements for the completion of the mission in 100%:
- Champion - you need to win the triathlon without taking shortcuts. The game will not punish you, fortunately, if you follow this walkthrough's suggestion, and land a bit to the left of the big bridge, while racing on the bike.