What are the adventures in Mark Twain's The Adventures of Tom Sawyer?I just don't know what events are considered as an adventure in the novel.

There are quite a few things that you could call adventures in this book.

Probably the two most obvious ones are the whole story of Huck and Tom and Injun Joe and, second, the adventure that Tom and Becky have in the cave.

The part where the two of them get lost in the cave is definitely an adventure.  After all, they are in danger of dying until they luckily find a way out.

The other story line is similar.  The two of them watch Injun Joe kill a man and then they are afraid for their own lives.  Then they find out about Injun Joe's treasure and have an adventure as they try to find out where it is (while avoiding Injun Joe and his revenge).