The 3.7-kilometer breakwater of Sri Lanka's Colombo Port City, stretching out like an arm to embrace the coastal area from high above, also resembles a flourishing garden teeming with corals and fish when viewed from underwater.

Piyal de Silva, a 60-year-old former commander of the Sri Lankan Navy, runs a diving school called "Coral Wall" inside the port city. A diving enthusiast from young, Piyal first discovered the thriving marine ecosystem in 2019.

Back then, as a major project under the Belt and Road Initiative, the Colombo Port City just completed its land reclamation. Diving nearby one day, Piyal discovered that coral was spreading and growing on the blocks of the breakwater.