The Adventure Party might be over, but you can still access the Big Kahuna and its temple! As far as I am aware you cannot get the items, although I would not recommend trying to get them just in case it bans your penguin.
To access the top of the temple, log in to Club Penguin with this link.
To go inside the temple, log into Club Penguin with this link.
You can then waddle through the temple to the other room.