A valve system for an inner tube assembly arranged to be used in a drilling system to retrieve a core sample created by the drilling system, the inner tube assembly being arranged to be insertable into a drill string of the drilling system at a first end of the drill string, the valve system being arranged to be configurable in a first closed configuration, an open configuration, and a second closed configuration, wherein: the valve system moves to the first closed configuration when fluid is pumped along an interior region of the drill string towards the inner tube assembly in a direction from the first end of the drill string to the inner tube assembly, the valve system being arranged such that, when in the first closed configuration, a pressure of the fluid increases to facilitate deploying the inner tube assembly towards a second end of the drill string; the valve system moves to the open configuration in response to the inner tube assembly reaching a vicinity of the second end of the drill string and being prevented from moving further towards the second end of the drill string, the valve system being arranged such that, when in the open configuration, fluid can flow to a drill bit located at or near the second end of the drill string; and the valve system moves to the second closed configuration when fluid is pumped along the interior region of the drill string towards the inner tube assembly in a direction from the second end of the drill string to the inner tube assembly, the valve system being arranged such that, when in the second closed configuration, the pressure of the fluid increases to facilitate retrieving the inner tube assembly from the vicinity of the second end of the drill string, the valve system further comprising a valve member and a valve seat with which the valve member can form a seal, characterized by the valve system being arranged such that the valve member is urged towards the valve seat into the first closed configuration to form a seal with the valve seat when fluid flows along the interior region of the drill string towards the inner tube assembly in a direction from the first end of the drill string to the inner tube assembly; wherein the valve member and the valve seat are arranged such that the valve member can be pushed through the valve seat to move the valve system into the open configuration in response to sufficient fluid pressure. the valve system moves to the first closed configuration when fluid is pumped along an interior region of the drill string towards the inner tube assembly in a direction from the first end of the drill string to the inner tube assembly, the valve system being arranged such that, when in the first closed configuration, a pressure of the fluid increases to facilitate deploying the inner tube assembly towards a second end of the drill string; the valve system moves to the open configuration in response to the inner tube assembly reaching a vicinity of the second end of the drill string and being prevented from moving further towards the second end of the drill string, the valve system being arranged such that, when in the open configuration, fluid can flow to a drill bit located at or near the second end of the drill string; and the valve system moves to the second closed configuration when fluid is pumped along the interior region of the drill string towards the inner tube assembly in a direction from the second end of the drill string to the inner tube assembly, the valve system being arranged such that, when in the second closed configuration, the pressure of the fluid increases to facilitate retrieving the inner tube assembly from the vicinity of the second end of the drill string, the valve system further comprising a valve member and a valve seat with which the valve member can form a seal, characterized by the valve system being arranged such that the valve member is urged towards the valve seat into the first closed configuration to form a seal with the valve seat when fluid flows along the interior region of the drill string towards the inner tube assembly in a direction from the first end of the drill string to the inner tube assembly; wherein the valve member and the valve seat are arranged such that the valve member can be pushed through the valve seat to move the valve system into the open configuration in response to sufficient fluid pressure.