Adjustable-length surgical access devices are disclosed herein, which can advantageously allow an overall length of the access device to be quickly and easily changed by the user. The access devices herein can reduce or eliminate the need to maintain an inventory of many different length access devices. In some embodiments, the length of the access device can be adjusted while the access device is inserted into the patient. This can reduce or eliminate the need to swap in and out several different access devices before arriving at an optimal length access device. This can also reduce or eliminate the need to change the access device that is inserted into a patient as the depth at which a surgical step is performed changes over the course of a procedure. Rather, the length of the access device can be adjusted in situ and on-the-fly as needed or desired to accommodate different surgical depths.