1. In 1951, The United States Navy's underwater sound laboratory, located in Kailua, Hawaii, confirmed that the low frequency sounds picked up by hydrophones were the sounds of Humpback Whales. This discovery revolutionized the study of marine mammal acoustics and led to further research on whale communication and behavior.

2. On December 20, 1989, the USS Missouri battleship was decommissioned in Bremerton, Washington. The ship is famous for being the site where the Japanese surrender was signed on September 2, 1945, ending World War II. The USS Missouri is now a museum ship at Pearl Harbor, Hawaii.

3. In 1962, Hawaii became the 50th state in the United States. After a long campaign by Hawaiian leaders and advocacy groups, President Dwight D. Eisenhower signed the Hawaii Admission Act on March 18, 1959, admitting Hawaii into the Union.

4. On December 20, 1824, the first group of missionaries arrived in Hawaii, led by Hiram Bingham. The group established the first Protestant church in Hawaii and played a significant role in the spread of Christianity throughout the islands.

5. In 1946, the Hilo Tsunami hit the Island of Hawaii, causing widespread damage and casualties. The tsunami was triggered by undersea earthquakes off the coast of the Aleutian Islands in Alaska, which sent massive waves across the Pacific Ocean. The Hilo Tsunami resulted in over 160 deaths and left many more injured or homeless.