Security Bypassed is a Challenge in the feats category.
- Board the yacht disguised as a security guard.
- Freeform Training - Already accessible if the mission is bought.
If you have an easier time learning by watching, you can check the video for a walkthrough of the challenge.
Start off by heading towards the three Yacht Security guards on the right side. One of them will be standing in a doorway by himself and the two others will have their back towards him. None of the guards will be suspicious of you despite wearing your Training Gear. Simply walk up to the little house where the one guard is standing and enter it through a window. You can now take out the guard silently from behind without the other two noticing. Once he is down you can put on his disguise and also hide his body in the closet located in the same room.
Now you need to be aware that one of the two guards will see through your disguise. When exiting the room you can sneak along the left wall until you are far enough away from him to not see you. If you picked up a coin on the table after spawning, you can also throw this towards the right side of the guards to make them look away. You can then simply walk past them towards the gangway. Once you are at the gangway, simply walk up and board the yacht to complete the challenge.