The land-ocean transition in the Arctic is a highly sensitive environment facing severe changes due to increasing temperatures. To assess these changes, the CACOON project conducted intensive fieldwork in the Russian Arctic with four field campaigns in 2019 in the Lena and Kolyma delta region. Lena Delta: In the Lena Delta region CACOON lead a 19 day spring campaign (CACOON Ice). Using a mobile camp on sledges, we were able to collect water samples, ice cores, surface sediments, gas samples as well as CTD profiles. For getting the terrestrial endmember, a Pleistocene permafrost cliff was sampled. During the summer campaign (CACOON Sea) more than 1300 samples were retrieved along a 200 km long transect from the centre of the delta into the Laptev Sea covering the freshsalt water transition. This expedition included sampling for the CAO-EISPAC project and revisited several sampling locations from the spring expedition to investigate seasonality. Kolyma Delta: The aim of field sampling was to capture the open water season (spring, summer and autumn) from the ice breakup in early June to re-freezing in late September. During the two long campaigns with 71 field days, we were able to sample the Kolyma River and the near shore area in seven independent transects. During that period, we collected more than 1200 samples, filtered and preserved for further analysis during the coming months. The collected sample material will arrive in Potsdam in December 2019. For requests, please contact Jens.Strauss@awi.de and paul.mann@northumbria.ac.uk Modelling the comparative influence of riverine input and coastal erosion on sediments in the Laptev Sea.