Many species of Kombu thrive in the waters around Hokkaido, Japan's northernmost island. The nutritious fronds are carefully selected according to the quality of the plant and the region in which it has grown. Of the different grades of kombu, the best (Hidaka #3) is gathered from the pristine Arctic waters off the coast of Hidaka Province. By late summer the kombu plants have grown up to 30 feet long and 6 inches wide. Men and women in small skiffs gather them by hand, using razor sharp knives attached to long bamboo poles to sever each plant at its stem. The kombu is then laid out on the stony beaches to dry slowly and naturally in the sun.