The swampland.
The Matsunashi Lake (松梨湖, Matsunashi-ko, Literally meaning "Pine Pear Lake") is a sacred location, that is dedicated to host the Crocodile summons. It is the equivalent to Mount Myōboku.
The emblem.
Due to the needs of crocodiles, it is a giant biome of wetlands, that is composed of lakes with stagnant water and filled with crocodiles. The soil is muddy and is fragile and slippery. The symbol of Matsunashi Lake is the kanji for "still water" (淀, yodo).