A connection assembly allowing a pipe (12) extending from the seabed (14) to be connected to a flexible pipe (26) leading to the sea surface (22). The assembly includes a turret (32) having an upper end (42) connected to a float (20) and a lower end (40) connected to the pipe (12). The turret (32) has a duct (50) extending towards the upper end (42) and having a free end (66) provided with an end fitting (68). The turret includes retaining members (70, 72, 74, 76) that keep the connector (30) between the turret and the end fitting, facing the end fitting (68). The connector (30) is in a fixed position in relation to the retaining members (70, 72, 74, 76) and a drive device (112) drives the end fitting (68) toward the connector (30).