Hi again, Ewan.
Here are your answers:
1)How will the octopus deal with the goggles the guy has on?
When the octopus bites the guy's head, the goggles will break in two and fall off.
2) what about the life jacket ,how it deal with that ?
As the octopus bites through the life jacket to get to the guy's body, it too, will be ripped to shreds by the octopus's strong beak and it will float away. The octopus will not be interested in anything but the guy's flesh.
3) would the ouctopus explore the guys body with it`s tentacles including the area in his trunks brofre starting to feed on him?
Yes, the octopus would be using its tentacles to explore the guy's body, including the area in his trunks, before starting to feed on him.
4) I have heard that ocpopus`s even large ones can squeese into tight confined spaces to feed ,could it do that with the area in the guys very tight swim trunks?
In this case, no, because the octopus would be too big and the very tight swim trunks would be too small; however, the octopus will start biting into the swim trinks to get to what's inside and the trunks, being of thin material, will also just be shredded and float away.
5) or would it just wrap its mantle around that area in the trunks and use it`s tentacles to try and pull the guys trunks off?
No, it would not try to use its tentacles to pull the guy's trunks off; it would just use it's sharp beak to get rid of the trunks to get to the guy's flesh.
6)what would it think of what it found in the guys tight swim trunks ?
It would enjoy what it found in the guy's tight swim trunks and would enjoy eating it.
7) how much of the guy could it eat in one go?
It would eat the guy in small parts and I would estimate it would take about 4-5 days for it to finish the guy, so about 1/4 of the guy in one go. It would keep the guy safe from other predators by keeping it in its lair.
8) what would be left of the guy and what would the octopus dow with it to keep it`s lair clean?
Basically, the guy's bones would be left and the octopus would sweep out its lair with its tentacles to keep it clean.
I hope this helped!