This study was conducted in the dolphinarium at the Kolmården Wildlife Park, Sweden, from May 2014 till March 2015. In the dolphinarium nine Atlantic bottlenose dolphins (Tursiops truncatus) were kept during the time of the study, with ages ranging from 1.5 to 41 years.
The dolphinarium consisted of two public display pools that were connected with a holding pool. The main observations were made in the  biggest of the two display pools, also referred as “the Laguna”. The water depth was 3m in the shallow area and 6m in the deep area.

Ten C-PODs (Continuous Porpoise Detectors ; Chelonia Ltd., UK; http://www.chelonia.co.uk/) and 2 PCLs (Porpoise Click Logger or AquaClick 100, Aquatec group Ltd., UK; http://www.aquatecgroup.com ) were used to monitor the dolphins’ echolocation clicks. Nine CPODs were attached to the bottom of the Laguna pool, and one to the bottom of the holding pool. The two PCLs were introduced in the Laguna later on during the study. Both the instrument hydrophones were suspended approximately 70 – 100 cm above the pool floor. In contrast with the CPODs, the PCLs do not float and needed two floats to keep them suspended from the pool floor. 
Since the devices were air filled, they provided a strong echo when hit by dolphin sonar clicks. The CPODs and PCLs automatically logged every click that was transmitted towards it and hence provided a measure of the echolocation activity.

The animals were filmed by two CCTV Raspberry Pi cameras, one mounted in the roof and one placed in front of an underwater acrylic panel. The roof camera, overviewing the major part of the Laguna, documented the dolphins’ swimming patterns, while the underwater panel camera documented  their close range interactions with a few of the CPODs and one of the PCLs. The cameras were programmed to record continuously every day from 06:00 to 18:00.