This Infiltration Points In Cayo Perico Heist In GTA Online Guide will tell you exactly where you must go on the island and what photographs you need to take in order to find them all. When you attempt the heist later in the DLC, you are given many different options depending on the evidence you have gathered.
I do the drainage tunnel and get inside when I get to half health without rebreathers, but yeah, rebreathers help. I only shot 2 guards, the one that patrols the front, but I shot him in that little gated area close to the main entrance, and the very topmost guard knocked out with a weapon and after I got the main target they found a bodyHow to do Cayo Perico door glitch in GTA Online. If you can't get the doors to open on PC, I would suggest connecting a controller just for this as it's much easier. As for the input timings, the general rule of thumb is to push the stick just slightly before L2/LT. Once you push the buttons, hold them until the door is open.
The primary target, secondary loot, bolt cutters, guard uniforms, and supply truck are the only things you have to scope out every time. But obviously not all are necessary. For Grand Theft Auto Online on the PlayStation 4, a GameFAQs message board topic titled "Another Cayo Perico glitch". Doing it on hard mode and whenever i try the drainage tunnel approach, the game tells me to go in through the north gate instead. ih8bVF.