A bottom hole assembly arranged for monitoring a well drilling operation while actively drilling said well, the bottom hole assembly comprising: a plurality of downhole, environmental sensors (202, 203, 220) comprising at least an accelerometer, a magnetometer, a gyroscope, wherein said environmental sensors are vibrationally isolated within said bottom hole assembly, the environmental sensors (202, 203, 220) arranged for collecting a set of measurements a signal processing device arranged for processing the set of measurements into a real time evaluation of a current location of the environmental sensors (202, 203, 220) by comparing data collected while actively drilling said well with data collected when the well drilling operation is not actively drilling the well; wherein the accelerometer, the magnetometer, and the gyroscope being vibrationally isolated comprises the accelerometer, the magnetometer, and the gyroscope being either: - mounted in an elongate configuration along with the signal processing device, the elongate configuration being supported by shock absorbers between a drill string associated with said well drilling apparatus and a drill face of a drill bit; or - mechanically isolated from a drill head assembly of said bottom hole assembly by one or more multi-degree of freedom vibration isolators; wherein the bottom hole assembly includes at least two modes of operation, including a continuous mode and a survey mode, the continuous mode being operational while actively drilling said well and the survey mode being operational at least during times when the well drilling operation is not actively drilling the well; the signal processing device being arranged for applying a first set of algorithms to a set of measurements collected while in said continuous mode of operation, the collected data and/or the results of applying said first set of algorithms to the set of measurements collected while in said continuous mode of operation being stored as stored data by said signal processing device; and the signal processing device being arranged for applying a second set of algorithms, different than said first set of algorithms, to a set of measurements collected while in while in said survey mode of operation to determine a calculated position of the downhole instrument package (i) from data collected from the set of measurements while in said survey mode of operation as augmented (ii) by the stored data. a plurality of downhole, environmental sensors (202, 203, 220) comprising at least an accelerometer, a magnetometer, a gyroscope, wherein said environmental sensors are vibrationally isolated within said bottom hole assembly, the environmental sensors (202, 203, 220) arranged for collecting a set of measurements a signal processing device arranged for processing the set of measurements into a real time evaluation of a current location of the environmental sensors (202, 203, 220) by comparing data collected while actively drilling said well with data collected when the well drilling operation is not actively drilling the well; wherein the accelerometer, the magnetometer, and the gyroscope being vibrationally isolated comprises the accelerometer, the magnetometer, and the gyroscope being either: - mounted in an elongate configuration along with the signal processing device, the elongate configuration being supported by shock absorbers between a drill string associated with said well drilling apparatus and a drill face of a drill bit; or - mechanically isolated from a drill head assembly of said bottom hole assembly by one or more multi-degree of freedom vibration isolators; - mounted in an elongate configuration along with the signal processing device, the elongate configuration being supported by shock absorbers between a drill string associated with said well drilling apparatus and a drill face of a drill bit; or - mechanically isolated from a drill head assembly of said bottom hole assembly by one or more multi-degree of freedom vibration isolators; wherein the bottom hole assembly includes at least two modes of operation, including a continuous mode and a survey mode, the continuous mode being operational while actively drilling said well and the survey mode being operational at least during times when the well drilling operation is not actively drilling the well; the signal processing device being arranged for applying a first set of algorithms to a set of measurements collected while in said continuous mode of operation, the collected data and/or the results of applying said first set of algorithms to the set of measurements collected while in said continuous mode of operation being stored as stored data by said signal processing device; and the signal processing device being arranged for applying a second set of algorithms, different than said first set of algorithms, to a set of measurements collected while in while in said survey mode of operation to determine a calculated position of the downhole instrument package (i) from data collected from the set of measurements while in said survey mode of operation as augmented (ii) by the stored data.