Young Thais are drawn by the big city lifestyle
Mosey over to the Big Island and book a B&B in South Kona for a few nights. For ocean adventures, hike to secluded Makalawena Beach, kayak and snorkel at Kealakekua Bay and snorkel or dive at night with manta rays around Kailua-Kona. In Kau, go caving at Kula Kai Caverns, hike to Green Sands Beach, and follow the rugged Road to the Sea. Next, Hawaii Volcanoes National Park offers spectacular hiking and, if you are lucky, a chance to watch live lava flow into the sea. Afterward, bed down in a rainforest cottage in Volcano. Spend a night or two in Hilo, taking time to day-hike on Mauna Kea or to drive partway up the mountain for stargazing after dark. Last, explore Waipio Valley; if you have the time, consider backpacking to Waimanu Valley.
With another week or more on Kauai, spend a couple of nights camping and hiking at Koke'e State Park and Waimea Canyon State Park, then boogie up to the North Shore, mixing some camping at Anini Beach or Haena Beach with lodgings in Hanalei. Swim, snorkel and surf, but do not leave without tackling the Na Pali Coast's amazing Kalalau Trail.