Some crocodile populations are notably present in marine environments. Within these environments, it is seldom considered how a crocodile’s skeleton may affect its swimming proficiency. All crocodylians possess flexibility-restricting ossifications within their skin, collectively referred to as their dermal skeleton. Crocodylus porosus (the Indo-Pacific crocodile) has a distinctly reduced dermal skeleton compared with other extant crocodylians. Existing publications on crocodylian biomechanics imply that a reduced dermal skeleton is advantageous for some swimming modes employed by crocodylians. To investigate further, we CT-scanned multiple C. porosus and C. johnstoni specimens to conduct an anatomical analysis. We found that C. porosus possessed a reduced dermal skeleton with a delayed ontogenetic development compared with C. johnstoni (Australian freshwater crocodile). We inferred that the morphology of the dermal skeleton of C. porosus may improve body flexibility for swimming modes that incorporate axial undulation when compared with other extant crocodylians. For C. porosus, greater lateral flexibility of the trunk and tail base may increase manoeuvrability for aquatic hunting and wider tail-strokes for more efficient swimming. The notable distribution and competitiveness of C. porosus in marine environments may support these implications. Future research should consider the potential ecological analogue C. acutus (American crocodile) in a kinematic comparison.