Lake in Ontario, Canada, is the largest kettle lake in Canada spanning . Fish Lake in the north-central Cascade Mountains of the U.S. state of Washington is . The depth of most kettles is less than ten meters. In most cases, kettle holes eventually fill with water, sediment, or vegetation. If the kettle is fed by surface or underground rivers or streams, it becomes a kettle lake. If the kettle receives its water from precipitation, the groundwater table, or a combination of the two, it is termed a kettle pond or kettle wetland, if vegetated. Kettle ponds that are not affected by the groundwater table will usually become dry during the warm summer months, in which case they are deemed ephemeral. Bogs If water in a kettle becomes acidic due to decomposing organic plant matter, it becomes a kettle bog; or, if underlying soils are lime-based and neutralize the acidic conditions somewhat, it becomes a kettle peatland. Kettle bogs are closed ecosystems because they have no water source other than precipitation. Acidic kettle bogs and fresh water kettles are important ecological niches for some symbiotic species of flora and fauna. The Kettle Moraine, a region of Wisconsin covering an area from Green Bay to south-central Wisconsin, has numerous kettles, moraines and other glacial features. It has many kettle lakes, some of which are 100 to deep. Examples The Prairie Pothole Region extends from northern Alberta, Canada to Iowa, United States and includes thousands of small sloughs and lakes. Austria Meerauge, Bodental Zmulner See, Carinthia (Kärnten) Canada Ontario Algonquin Park, Spruce Bog trail Bond Lake Heart Lake Kettle Lakes Provincial Park Lake Wilcox Musselman Lake Preston Lake Puslinch Lake New Brunswick MacLaren Pond, Fundy National Park Finland Syvyydenkaivo, Rokua National Park Germany Eggstätter Seen, Bayern Müggelsee, Berlin Oberwaldbacher See, Bayern Osterseen, Bayern Schluisee, Bayern Seeoner Seen, Bayern Teupitzer See, Brandenburg Tüttensee, Bayern Ukleisee, Schleswig-Holstein Weisser See, Berlin India Sela Pass, Arunachal Pradesh New Zealand Lake Matheson United Kingdom England Aqualate Mere, Staffordshire Barelees Pond, Northumberland Breckland, Norfolk/Suffolk called pingo ponds. Bomere Pool, Shropshire Campfield Kettle Hole, Northumberland Hatchmere, Cheshire Talkin Tarn, Cumbria Tarn Wadling, Cumbria Wormingford Mere, Essex Scotland Belston Loch Blae Loch Helenton Loch Loch Brown Loch Fergus Loch Morlich United States Illinois Volo Bog Indiana Pinhook Bog Iowa Clear Lake Massachusetts Cliff Pond Fresh Pond Jamaica Pond Houghton's Pond Scargo Lake Spy Pond Walden Pond Michigan Heart Lake Tee