The Surprise occurrence is located at timberline on the south side of Pine Creek valley, northeast of Spruce Mountain, about 15 kilometres east of the community of Atlin.

The area is underlain by basalts of the upper Mississippian to Permian Nakina Formation (Cache Creek Complex) and upper Mississippian to Permian ultramafics. The ultramafics are spatially related to these Cache Creek rocks and Monger (Geological Survey of Canada Paper 74-47) believes they may be genetically related as well. Contact with the Late Cretaceous Surprise Lake batholith (Surprise Lake Plutonic Suite) occurs within several kilometres to the northeast.

Locally, irregularly distributed quartz veins, from less than 1 centimetre to 6 metres in width, strike 170 degrees and dip 70 degrees southwest through basalt and ultramafic rocks (carbonatized serpentinite) near their contact. The ultramafic (listwanite) band varies from 3 to 25 metres in thickness and has been traced over a strike length of 400 metres. The quartz veins contain minor amounts of galena, pyrite, chalcopyrite, siderite and calcite. The rocks are talc-carbonate to silica-carbonate altered while fuchsite and mariposite are common and are generally related to the intensity of quartz veining. Some galena clots are up to 4 centimetres across.

Exploration of a 3.6-metre-wide quartz vein with an adit prior to 1925 revealed minor amounts of argentiferous galena, pyrite, chalcopyrite, and siderite.

In 1980, a series of bulldozer trenches, located north of the adit, exposed a carbonatized serpentinite (listwanite) containing pyrite and pervasive mariposite yielding up to 0.62 gram per tonne gold in chip samples (DuPre, D.G. (2010-03-08): National Instrument (NI) 43-101 Technical Report on the Surprise Lake Property). In 1982, sampling of the occurrence by Standard Gold Mines Ltd.) yielded values of up to 1.27 grams per tonne gold and 36.58 grams per tonne silver (Assessment Report 11138).

In 2006, Double Crown Ventures Ltd. carried out magnetic (9.9 kilometres), VLF-EM (4.5 kilometres) and induced polarization/resistivity (1.8 kilometres) surveys on the Surprise showing grid. In 2007, Double Crown Ventures carried out Mobile Metal Ion (MMI) soil sampling on four different grids within the Surprise Lake property. The MMI sampling consisted of 1060 samples taken along two lines for a total survey length of 1800 metres. In 2010, a computer-based structural analysis to satellite images of the property and nearby areas was completed on behalf of Double Crown Ventures Ltd.

In 2015, a MMI soil sampling survey was conducted on behalf of DeCoors Mining Corp. and a total of 64 samples were collected on two parallel east-west lines 100 metres apart at 25-metre intervals. A total of 12.9 line kilometres were surveyed. In 2017, Decoors Mining Corp. completed an induced polarization (IP) geophysical survey, MMI geochemical sampling (302) and geological mapping on the Otter Creek block of the Surprise Lake property. A total of eighteen lines of IP were collected covering a total of 12.9 kilometres on and around the Otter Creek placer operation (104N 032). In 2019, Decoors Mining Corp. completed an exploration program on the Otter Creek project designed in follow up the discovery of two separate visible gold occurrences in the Otter Creek placer pits. In total, 465 soil samples (229 MMI, 226 SGH) and 58 rock samples were collected. In addition, geological mapping and 143 kilometres of magnetometer and 2.45 kilometres of IP surveys were completed.