Many aquatic organisms locomote using body-caudal-fin oscillatory motions. Within elasmobranchs, the shortfin mako is considered the most hydromechanically efficient species. They have evolved numerous morphological adaptations to enhance their hydromechanical efficiency. For this study, we considered the lunate caudal fin and thunniform oscillations shortfin Makos employ to propel themselves. Most elasmobranchs have a heterocercal caudal fin paired with carangiform oscillations. This study investigated the hydrodynamics of the shortfin mako using a flexible scale model with a robust oscillating caudal fin that emulates this species’ natural thunniform body motions. Here, the shortfin mako’s lunate caudal fin was replaced with the heterocercal caudal fin common to other sharks; a comparison between the wake characteristics of two morphologies was performed to shed light on the effects caudal fin morphology has on hydrodynamics when paired with thunniform oscillations. Experiments were conducted in a recirculating water flume using particle image velocimetry (PIV) to measure the wake velocity field formed behind each oscillating caudal fin. The velocity fields were used to estimate the sectional drag formed during steady forward swimming, as well as the near-wake turbulence characteristics. Results indicate that the different morphologies generated similar wake characteristics, yet there was a notable discrepancy in the energetics and size of the wake, where the lunate tail had a narrower, more energetic wake, especially in terms of rotational fluid motion. Due to these features, the wake also decayed more slowly as the distance from the caudal fin increased.