How does the island symbolize the immoral character of the treasure hunting expedition?

The island is wild, untamed, and inhospitable.... it mirrors the behavior of the mutineers.

In this concluding chapter, the all important symbol is, of course, money. From the beginning of the book, this has been a reoccurring symbol and metaphor, but as Jim looks at the gold currency as he packs it into bags to be transported, he reflects not only upon the wealth that is at his fingertips, but also upon the cost that this money has had: seventeen men have died for this wealth. Money, therefore, in Treasure Island is a symbol of corruption - even the straight-laced and proper Dr. Livesey has not been unaffected by the influence of money.