The culture discussed in this article, the late Mesolithic Ertebølle (EBK) culture, is famous for its large coastal shell middens. In the past, it was assumed to be a purely coastal phenomenon (Gjessing 1955), but the inland was settled as well (Noe-Nygaard 1983; 1987; Madsen 1986). In the Åmosen region of Sjælland, Denmark, for example, about 100 inland Ertebølle sites are known (Andersen 1983). However, inland sites have not received the same attention as coastal sites (Blankholm 2008; Thorpe 1996). Inland settlement may have been scarce at the beginning of the EBK, but increased during the later EBK (Dellbrügge 2002; Fischer 1993; 2002b; Schilling 1997; 2003). Inland sites were generally smaller and settled for shorter periods of time than coastal sites (Andersen 1993), although larger inland sites are also known (Petersen 1987). The Danish sites Vester Ulslev and Godsted, for example, both situated on small islands in lakes, were exclusively summer sites, but represent large occupational units (Petersen 1973).
At inland sites, a wide variety of freshwater resources was exploited. Cultural layers at Mesolithic sites in the Åmose bog area contain bones and scales from freshwater fish and shells from freshwater molluscs. The site of Præstelyngen, for example, was dominated by pike bones (Noe-Nygaard 1983; 1987). The significance of freshwater resources for the Ertebølle culture is demonstrated by the efforts put into the construction of stationary fishing devices. Around Ringkloster in Jutland, fish fences made of long and slender hazel stakes were found. Together with pollen evidence, this indicates the coppicing of hazel (Andersen 1994-95).
In Schleswig-Holstein, the Rivers Trave, Alster, Bille and Stecknitz were important locations for fishing and hunting stations from the Mesolithic to the Bronze Age (Schirren 1997). The Satruper Moor, a former lake at the Bondenau River, provides another example of a concentration of sites (Schwabedissen 1960). Artefacts found at inland sites attest freshwater fishing: e.g. leisters, netfloats and nets from the sites Rüde 2 and Förstermoor in Schleswig-Holstein (Schwabedissen 1960; 1980).
Aquatic plants might also have formed an important part of Mesolithic nutrition, although they are less visible archaeologically than freshwater fish and molluscs. There is evidence for the collection of water chestnuts, water-lily seeds and reed mace (Tilley 1996; Holst 2010). The favoured Mesolithic settlement sites at lagoons, estuaries, shallow lakes and fen carrs might have been chosen for their wealth of rhizomes and tubers (Tilley 1996).
Handmade pottery first appears in this region in the later EBK (c. 4500–4000 cal BC), in two forms: a flat, elliptical bowl interpreted as a lamp, and a deep, open vessel with a pointed base and a decorated rim, regarded as a cooking pot (Hartz 2011). Biomolecular analysis of absorbed lipids confirms that pottery was used for these purposes, and a significant proportion of pots tested have produced biomarkers associated with aquatic species (Heron et al. 2013; Craig et al. 2011).