Deep in situ rock stress determinations are typically conducted using hydraulic fracturing in an existing borehole or by applying specialized overcoring techniques that require the installation of a strain-monitoring instrument in a central pilot borehole that is subsequently overcored. The unusually high horizontal to vertical stress ratio at depth in Canada's Underground Research Laboratory (URL) results in problems in the application of either of these methods. At 420-m depth, the rock in the URL is massive granite with virtually no fractures. The maximum principal stress is approximately 60MPa and is sub-horizontal. The minimum principal stress is only 11MPa, resulting in a horizontal to vertical stress ratio of almost 6 to 1. In these conditions, hydraulic fracturing is unable to produce axial fractures in sub-vertical boreholes or is unable to fracture the rock at all. Overcoring methods requiring a pilot hole are not feasible because of persistent core discing. To resolve these problems, AECL has applied a remote data logger/signal conditioner to the design of a Deep Doorstopper Gauge System (DDGS) for use to 1000-m depth. The DDGS is much less susceptible to core discing than most other overcoring methods because it does not require a pilot hole. This paper describes the operating principle of the DDGS and the results of field testing at the URL, as well as issues related to its use and the interpretation of results.