The Cawthron Institute, a non-profit scientific research center in New Zealand, has released a report about the ability of sea chests to harbor non-native marine organisms. Before you form a picture in your mind of a treasure chest sitting at the bottom of the ocean, brimming with jewels and invasive species, you should know that a sea chest is actually a recess built into the hull of a ship. Each sea chest is covered with a grating, and can be a great hiding place for creatures who can't take exposure to the fast water flow around the outside of a ship. The above link only goes to a summary page; be sure to click on the "Read more..." link to see the full report (.pdf format).
(Thanks to a member of the ALIENS-L listserver for posting a link to this article)