Japan has built one of the world’s most ambitious coastal defences, a 12.5-metre-high seawall stretching almost 400 kilometres.
The massive structure, known locally as the “Great Tsunami,” was developed after the 2011 disaster which killed nearly 20,000 people.
That catastrophe exposed the vulnerability of coastal towns, where towering waves destroyed communities and left lasting scars along the shoreline.
Engineers designed the wall to withstand waves carrying 16 million tons of water, with nine million trees planted as added defence.
These trees form part of the “Great Forest Wall Project”, a plan to grow disaster-preventive coastal forests to absorb tsunami energy.
Once mature, the forests act like a living shield, slowing waves, trapping debris, and strengthening natural resilience against future disasters.
Japan is one of the most tsunami-prone nations on Earth, and such defences are now seen as vital for survival.
Concrete seawalls are not intended to stop tsunamis entirely but to reduce their force and, crucially, buy evacuation time.
Officials emphasise that even a few extra minutes can mean the difference between mass survival and catastrophic loss of life.
Construction was a vast engineering feat, with foundations buried 25 metres underground and reinforced inner walls resisting repeated wave strikes.
In places like Tarō, walls stretch for over two kilometres, so tall that residents must climb 30 steps to view the sea.
Critics say the grey walls scar the landscape, but the green forests provide a softer, ecological balance to concrete might.
Together, seawalls, trees, and improved warning systems form a layered defence strategy, reshaping coastlines and redefining resilience in tsunami-stricken Japan.
