Material/methods: Five different detectors were tested for determining the surface dose in water: EBT3 and HD-V2 GAFCHROMICTM radiochromic film, LiF:Mg,Ti thermoluminescent dosimeter, IBA PPC05 plane-parallel ionization chamber, and PTW 23391 extrapolation chamber. The irradiation setup consisted of quasi-monoenergetic scanned proton pencil beams with kinetic energies of 100, 150, and 226.7 MeV, respectively. Radiochromic films were placed within a vertical stack and in wedge geometry and were analyzed with FilmQA ProTM adopting triple channel dosimetry. The extrapolation chamber PTW 23391, which served as a reference in the current work, was used in a conventional ionization chamber setup with a fixed electrode gap of 2 mm. Three Kapton_ entrance windows with thicknesses of 25, 50, and 75 μm were employed. Thermoluminescent dosimeters were provided as powder and were pressed onto a sheet of aluminum. Furthermore, the Monte Carlo code TOol for PArticle Simulation (TOPAS) in version 3.1.p2 was used to model an IBA pencil beam scanning nozzle and score dose to water in a water phantom.