The aim of this paper is to discuss some basic factors regulating sediment variability, namely bottom dynamic conditions, sediment contamination, lake size, and lake bottom irregularity, based on empirical data from Swedish lakes. Figure 1 is meant to illustrate a fundamental problem in sediment sampling. Consider an area (a lake, a given stretch of a river, etc.) from which there are no data (all is black). One sediment sample (Figure 1A) will reveal the sediment characteristics at the sample site, and from this it is possible to make predictions about the situation near the site. But how near is near? And how many samples (n) would be required to obtain a mean, median, or characteristic value for the entire lake? And what are the most important factors that influence this number? These are fundamental questions in all contexts where recent sediments are used (e.g., in aquatic pollution control programs for metals or other types of pollutants and in matters dealing with the evaluation of sediment toxicity). Ilustration of the “torch” concept in sediment sampling. https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9781351076555/56e7a433-e1a7-4767-b6be-9c1fc62cf56c/content/fig2_1.tif"/>