Horizontal Directional Drilling enables the drilling of horizontal boreholes 50 mm (2 inches) to 1200 mm (48 inches) in diameter beneath surface/subsurface obstacles, over extended horizontal distances. Recently, this technology has expanded its application beyond the oil, gas, and utilities industries to include the sampling and logging of soils in geotechnical site investigations. This paper provides a short introduction to horizontal directional drilling. Horizontal sampling and logging tools including a prototype multiple-port soil sampler and a horizontal directional pre-bored cone penetration device (HD-PB-CPT), currently under development as part of an academia/industry collaborative research program, are described. Overall, horizontal directional drilling technology has valuable applications in site investigation, offering a more efficient and cost-effective method for collecting geotechnical and geo-environmental data.