The Arctic climate underwent strong modifications over the past decades. Thanks to a data base gathering more than 18000 observations collected in the entire deep basin of the Arctic Ocean since 1997, we focused on the interannual variability of the upper ocean. The subsurface Summer Pacific Water warmed up since the late 1990s. Notably, a particularly warm flux entered the Arctic Ocean in 2004 was documented all along its propagation in the Canadian basin. These analyses suggest a possible influence of the subsurface waters on the sea ice evolution in the Arctic region. At depth, observations confirm the propagation of warm Atlantic water pulses, in particular a warm anomaly of 0.8°C detected for the first time in 2004 West of Svalbard. Nevertheless, we did not find evidence for any gradual warming trend of this water mass. The double diffusion process seems to be a widespread phenomenon in the entire deep basin. The vertical heat fluxes transmitted through the interfaces between two mixed layers increased since the 1980s, notably because of the "supersteps" appearance, characterized by a strong temperature increase at the interface. Above the thermocline, the halocline remained relatively robust over the past decade. Its stratification intensified in 2007-2008 in the Canadian basin due to a freshwater content increase probably in response to the atmospheric forcing. As a consequence, the warm Atlantic waters remained insulated from the surface waters and did not contribute to the changes observed at the surface over this period.