The quantification of intra-population niche variation including individual specialization can provide valuable implications for population dynamics and behavioral adaptations. Laticauda semifasciata is a marine snake which preys on various fish taxa in a wide range of depths and substrate types. We investigated intra-population trophic variation in this generalist species using stable isotope analysis of carbon and nitrogen. For analysis, ventral scales, red blood cells, and plasma were sampled from adult snakes (12 females and 19 males) at Ishigaki Island. The overall isotopic values of L. semifasciata were characterized by a wide range in δ¹³C and relatively limited range in δ¹⁵N. Females were larger in body size and had significantly lower δ¹³C values than males. Multi-tissue stable isotope analysis revealed extreme individual specialization in δ¹³C, and to a lesser extent, in δ¹⁵N as well. The relatively depleted ¹³C in females may reflect a higher reliance on deeper, pelagic foraging grounds, facilitated by increased diving capacities due to having a larger body. Our results of individual specialization suggest that despite exploiting a wide range of habitats at the population level, individual L. semifasciata likely use limited habitat types or possibly locations to feed, where they adopt habitat-specific foraging tactics.