King Kong (1933) : The Man Who Would Be King (1975)
The Treasure of the Sierra Madre (1948) : Hidden Fortress (1958)
Lawrence of Arabia (1962) : Time Bandits (1981)
Lost Horizon (1937) : Raiders of the Lost Ark (1981)
She (1935) : The Golden Voyage of Sinbad (1974)
I have a very specific definition for what I term an 'adventure film', though I must say it's a definition that is rather fuzzy round the edges, and I find it difficult to pin down in words. It's got something to do with having to go on a journey, maybe a quest of some kind, and it's got something to do with starting out in the ordinary and being led off into the extraordinary. It may also have something to do with genre to some degree - The Lord of the Rings trilogy are definitely adventure films, but I don't quite categorise them as such due to the fact they take place in a fantasy world. Likewise, The Guns of Navarone or A Bridge Too Far are adventure films but, for me, the category of 'war film' trumps the category of 'adventure film'.
If you have any suggestions for good adventure films, please do let us know!