A method and a device for enabling the use of riserless drilling fluid recovery from a seabed-based borehole (1) which is to be drilled by means of a casing (26), the casing (26) being provided with a drill bit (28) at its lower portion and with an inner wellhead (30) at its upper portion, and there being a conductor casing (6), which has an outer wellhead (8), in the seabed (2), the method including: —providing a suction module (12) with a dividable adapter (16) which fits complementarily in the outer wellhead (8); —drilling a length of the borehole (1) by means of the casing (26) extending through the suction module (12), while, at the same time, drilling fluid is flowing via the suction module (12) from the borehole (1); —subsequently pulling the adapter (16) up from the outer wellhead (8) and dividing the adapter (16); and—lowering the casing (26) with the inner wellhead (30) through the suction module (12) and the adapter (16) to its position in the outer wellhead (8).