Dive computers have an important potential for citizen science projects where recreational SCUBA divers can upload the depth temperature profile and the geolocation of the dive to a central database which may provide useful information about the subsurface temperature of the oceans. However, their accuracy may not be adequate and needs to be evaluated. The aim of this study is to assess the accuracy and precision of dive computers and provide guidelines in order to enable their contribution to citizen science projects. Twenty-two dive computers were evaluated during real ocean dives for consistency and scatter in the first phase. In the second phase, the dive computers were immersed in sufficient depth to initiate the dive record inside a precisely controlled sea aquarium while using a calibrated device as a reference. Results indicate that the dive computers do not have the accuracy required for monitoring temperature changes in the oceans, however, they can be used to detect thermoclines if the users follow a specific protocol with specific dive computers. This study enabled the authors to define this protocol based on the results of immersion in two different sea aquarium tanks set to two different temperatures in order to simulate the conditions of a thermocline.