Right off the famous Waikiki Beach in Honolulu is the towering Diamond Head State Monument, one of Hawaii's top hiking destinations. Diamond Head is a 300,000-year-old crater that peaks at 761 feet above sea level. If you're planning on ascending the former volcano, be aware while it's not a particularly long hike -- less than a mile from the trail head to the summit, one-way -- it does ascend 560 feet, and there are dozens of steps and a dimly lit tunnel to navigate. But the views are well worth the roughly two-hour trek. On a sunny day, you can see the islands of Molokai and Lanai in the distance.