Abstract: An apparatus (10) for preserving biological material. The apparatus (10) has an insert (4) configured to be arranged within an outer insulated tank (2), the insert (4) defining a compartment (6) for receiving biological material. Inflow of a heat exchange fluid into the compartment (6) from the outer insulated tank (2) is at or adjacent one face of the insert (4), while outflow of the heat exchange fluid out of the compartment 6 to the outer insulated tank (2) is at or adjacent said face of the insert (4). The compartment (6) has a wall having a series of apertures to accommodate a continuous heat exchange fluid flow through the apparatus such that, in operation, biological material in the compartment (6) is immersed in the heat exchange fluid to exchange heat with the heat exchange fluid for freezing of said biological material.