Another large, concrete dock, similar to the one that washed up in Oregon this summer, was found floating in the Pacific Ocean.
Fishermen first spotted the dock last week near the Hawaiian island of Maui and then the next day near Molokai.
A plaque written in Japanese was found on the dock, the fishermen told authorities.
It was predicted to come ashore around Oahu within a few days. However, it hasn't been spotted since.
The Coast Guard is warning other marine craft to be aware of the dock and more possible debris from the 2011 tsunami.