A declining trend of Antarctic Krill biomass has be documented in concert with an decrease in winter sea ice duration in the Atlantic sector of the Southern Ocean since the mid seventies, suggesting that larval krill development during winter might be a key factor to understand the stock development of krill. Correlative studies make us aware that krill might be sensitive to environmental changes but cannot answer the question why. Therefore our goal was to go beyond collative studies towards a mechanistic understanding between larval krill and sea ice to understand which winter sea ice condition might favour larval krill development and hence recruitment success of krill. During two dive camps, established on an ice floe (9 and 14 days respectively), as well as two zodiac dives, we did an intense under ice survey on larval distribution and abundance in relation to under ice topography and biomass as well as larvae behaviour. In the presentation, Prof. Bettina Meyer will give an overview of the diving operations and show first results of the winter expedition in the Northern Weddell Sea in 2013.