Knowledge about swarm dynamics and underlying causes is essential to understand the ecology and distribution of . We examined swarms across the South Orkney Islands in March and April 2017 using the Simrad EK60 (38 and 120 kHz) echosounder, concurrent with net sampling. The acoustic data were analyzed by applying a swarm-identification algorithm, and then filtering out all non-krill targets. A total of 2539 krill swarms with swarm characters including swarm height and length, packing density, swimming depth, and inter-swarm distance were extracted, of which 1389 were daytime swarms and 1150 night swarms. Compared with those of the night swarms, krill aggregated in deep waters during the daytime with lower packing density and smaller inter-swarm distance. There were significant differences between day and night krill swarms. Through the multivariate analysis, the krill swarms were divided into three categories, which differed in both their dimensions and packing density. Group A presented the highest swarm density[(19.24±27.00) ind/m³], Group B swarms presented the deepest distribution depth[(174.74±53.30) m], Group C presented the largest swarm area[(2868.62±2149.75) m²] with the longest swarm length[(258.76±322.88) m]. There was no significant difference in swarm length between Groups A and B and no significant difference in swarm depth between Groups A and C. Group A swarms were mainly distributed in deep water areas in the north and northwest regions of the South Orkney Islands at a depth of >1000 m, and mainly occurred during daytime. Groups B and C swarms were distributed throughout the survey area; Group B swarms were aggregated in the continental shelf at a water depth of <200 m. The results suggest that the majority of krill were contained within a minor fraction of the total number of swarms, and there was a positive correlation between packing density and inter-swarm distance. The results also provide valuable information on the distribution of krill swarms in this area and basic data for the current feedback krill resource management of Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). In the future, studies on the correlation between krill swarms and external factors, such as environmental factors and predators, can help understand the swarm structure and formation mechanism more accurately and predict the distribution of krill resources.