Holkham Bay is a bay in the U.S. state of Alaska. It connects Tracy Arm and Endicott Arm on its east to Stephens Passage on its west. Holkham Bay was named for Holkham, a community in Norfolk, England by George Vancouver. The Tlingit knew the bay as Sum Dum, reportedly referring to the sound of ice falling off glaciers into the water. This led to the alter…Holkham Bay is a bay in the U.S. state of Alaska. It connects Tracy Arm and Endicott Arm on its east to Stephens Passage on its west. Holkham Bay was named for Holkham, a community in Norfolk, England by George Vancouver. The Tlingit knew the bay as Sum Dum, reportedly referring to the sound of ice falling off glaciers into the water. This led to the alternate name of Sumdum Bay in use today. Some mines in the area borrow both names.