This paper provides an overview of currently-available data recorders for use in research on marine animals. These recorders are deployed on freely swimming animals and gather data on aspects of an animal’'s diving behaviour. The records can be recovered in one of two ways: the data recorder must either be recovered intact, or the data recorder must be capable of disseminating its data via a radio link, such as the ARGOS satellite system. Recorders can be further subdivided into raw-data and processed-data recorders. Raw-data recorders keep a complete record of the diving parameters of interest and thus produce extensive records, whereas processed-data recorders only report summary statistics which may be quite brief. Due to the limited data-handling capacity of the ARGOS satellite system, most satellite-linked recorders will necessarily report processed data.