to explore the ocean’s depth,about 3 kilometers down,way dee

to explore the ocean’s depth,about 3 kilometers down,way deep to ocean floor
to explore the ocean’s depth,about 3 kilometers down,way deep to ocean floor.其中way deep不是很理解
No one had ever explored that far down before.句子中down是不是修饰副词far,一个副词修饰另一个副词是不是一般都放在其后?
或许应该是that far修饰down吧，都糊涂了！