The River and the Waterfall

Hint: Why is everything so dark?

Hint: Who is that black knight?

Hint: Where is this crystal for the knight?

Hint: How do I get across the river?

Hint: I just got swallowed by a carp!

Hint: How do I get out of the carp?

Hint: What do I do at the waterfall?

Hint: What do I do with the dragon?