Unprovoked mouth gaping behavior is ubiquitous throughout 24 extant members of Crocodylia, yet information on gaping is limited. Proposed hypotheses for gaping include thermoregulation and the evaluation of potential environmental conditions. To determine temperature effects, we tracked head surface (T_sh), body surface (T_sb), and ambient (T_a) temperatures with insolation utilization and positions. To evaluate potential environmental stimuli, we tested behavioral effects (i.e., open-eye frequency) and recorded conspecific presence, day and night events, and interaction with flies and fish. We included 24 extant species representatives, with detailed assessments of American Alligators (Alligator mississippiensis), Crocodylus siamensis, Crocodylus intermedius, Crocodylus rhombifer, and Crocodylus halli. Observations occurred during a range of T_a (3.89–32.22°C) with mean T_sh consistently higher than both T_sb and T_a across all crocodilians. Differences in T_sh and T_a were most pronounced with head in the sun. However, no significant differences in T_sh and T_sb were detected for A. mississippiensis and Cr. siamensis. Conversely, Cr. halli, Cr. intermedius, and Cr. rhombifer demonstrated statistically higher T_sh. Gaping with open eyes was more common, yet modeling suggested a relationship with closed eyes and temperature. Anecdotal observations indicated weather changes may elicit mouth gaping, and we report the second nocturnal mouth gaping observation (the first for three species). Overall, mixed results indicated unprovoked mouth gaping is a complex behavior, making it difficult to draw clear cause and effect relationships. Future research may benefit from a focus on natural history and quantitative behavioral studies.