Abstract: There is provided a monitoring system (300) for monitoring within a borehole (10). The system (300) comprises a probe assembly (100) operable to be moved within the borehole (10) for sensing one or more physical parameters therein, a data processing arrangement (110) located outside the borehole (10), and a data communication link (120) operable to convey sensor data indicative of the one or more physical parameters from the probe assembly (100) to the data processing arrangement (110) for subsequent processing and display and/or recording in data memory (140). The probe assembly (100) includes one or more sensors (320) for spatially monitoring within the borehole (10) and generating corresponding sensor signals (360).