Routine snow survey and snow gauge data provided by weather stations establish snow-on-the-ground and snowfall time series but they lack a spatial dimension. Of particular importance to arctic hydrology is the end-of-winter snow conditions. For micro-scale investigations of spring breakup, slope runoff generation or gully sediment production, detailed mapping of the late winter snow cover is required. On a meso-scale, terrain exerts the principal control on snow distribution so that for catchment snowmelt and water balance studies, terrain units should be distinguished and the snow water equivalent for various terrain types obtained through ground survey. Regional dispositon of the snowline or early melt zones can be mapped from satellite but ground truthing is necessary if the quantity of snow needs to be known. Passive microwave sensor offers the potential of mapping the snow water equivalent after the signals are calibrated by ground snow data. Spatially distributed but areally integrated rather than point snow data are appropriate for macro-scale hydrological investigations. Field studies carried out in the Canadian Arctic Islands over the past decades provide the database and the experience needed to recommend appropriate methods for acquiring snow cover information compatible with the scale and the subject of enquiry.