Any gamers know of any fun 2-player adventure games for the Playstation 2?
Could you define “adventure game”? Some examples (even of one player ones) would be useful. 
Yeah, when I think of adventure games, I can’t think of anything that could have more than one player.
Adventure games are the ones that have missions and puzzles that you must solve. They can mix action; but the quests are the main distinction. The Spyro series are a good mix of action and adventure; but they’re one-player. I’d like something like that you play cooperatively.
Bugs Bunny & Taz: Timebusters is the only 2-player game I’ve seen that has that.
My SO and I really enjoyed both Baldur’s Gate games, and the less good (but nostalgic for me) Brotherhood of Steel.
ZJ
Hmm. You might like the two X-Men games (One and Rise of Apocalypse), which can be anything up to four-player games. Quests and puzzles, yes, but the emphasis is pretty heavily on fighting, so you might not enjoy it.
The later Splinter Cell games have a two-player mode, which is again questy/puzzly but with the emphasis on stealth and a reasonable amount of action (depending on how good you are at the stealth 
).
And there’s always Katamari Damacy, which is really a party game, but is surprisingly good fun.
I’ve heard good things about The Adventures of Cookie & Cream, which is a bizarre action puzzle game. Each player runs down their own half of the scrolling screen (two players are mandatory), and if I remember correctly, the goal is to complete the level before time runs out. All of the puzzles involve cooperation, and it supposedly gets quite involved later on. I only played a bit, and it got tricky fast.
It’d be pretty hard to find these days, but it’s the only thing that comes to mind when I think about 2-player adventure or puzzle games.