Artificial coastal lighting disorients sea turtle hatchlings, which instinctively move toward the brightest horizon. Instead of reaching the ocean, thousands are led inland each year where they die from exhaustion, dehydration, or road traffic.
The suffering caused by light disorientation is substantial and measurable. Hatchlings that move inland rather than seaward exhaust their yolk reserves — the only energy they carry — within hours. Many die slowly from dehydration and heat exposure, or are killed in road traffic. This occurs on a large scale: tens of thousands of hatchlings are disoriented annually in Florida alone. Adult turtles that are disturbed by lighting may abort nesting attempts, swim offshore to repeat the process, or select suboptimal sites. Reducing coastal light pollution is a direct intervention that reduces this suffering at minimal cost.