At least 43 percent of Japan's coastline is lined with concrete seawalls or other structures designed to protect the country against high waves, typhoons or even tsunamis. During the 2011 Tōhoku earthquake and tsunami, the seawalls in most areas were overwhelmed. In Kamaishi, waves surmounted the seawall — the world's largest, erected a few years ago in the city's harbour at a depth of , a length of and a cost of $1.5 billion — and eventually submerged the city center.