Drive twenty-five minutes uphill from Kahului and Maui stops being a beach. The Haleakalā Highway climbs through the old cane land into pasture, the temperature drops ten to fifteen degrees, the air smells of eucalyptus rather than salt, and you start seeing fence lines, horses and cattle grates. This is upcountry: the western slope of the volcano between roughly 1,500 and 4,000 feet, running from Makawao through Pukalani and Kula up to Keokea and out to ʻUlupalakua. It has its own weather, its own agriculture and its own sense of itself, and a great many visitors who spend a week in Wailea never see it at all.
The history is ranching, not tourism. Cattle arrived in Hawaiʻi as a gift to Kamehameha I in the 1790s and were left to multiply until they became a problem, and in the 1830s Kamehameha III brought Mexican vaqueros from California to teach Hawaiians to manage them. The Hawaiian word for those cowboys, paniolo, comes from español, and paniolo culture on Maui predates the American cowboy of the mainland West. Makawao is where that history is still visible: a one-junction town of false-front timber buildings, saddleries, galleries and a bakery, which hosts one of the biggest rodeos in the state around the Fourth of July.
The agriculture is what makes it worth a day now. Elevation, volcanic soil and a reliable temperature range mean things grow up here that will not grow at sea level. Protea, a South African flower with an alien, architectural look, thrives on this slope and is shipped worldwide from Kula. Lavender is farmed at around 4,000 feet. Sweet Kula onions, strawberries, lettuces and coffee come off the same hillside. There is a goat dairy making cheese, a distillery growing its own sugarcane, a pineapple company still farming at Hāliʻimaile, and a winery at ʻUlupalakua that has been planted since the 1850s and once poured for King Kalākaua.
Context matters for that last point. Maui's plantation economy is recent history rather than ancient: Hawaiian Commercial and Sugar took the island's final commercial sugar harvest in December 2016, ending more than a century of cane in the central valley, and large-scale pineapple wound down before it. What you are driving through upcountry is farmland working out what it is now, which is why so much of it is open to visitors. The farm tours are not theatre. They are a second income stream for working agricultural businesses.
Practically, it is the best pairing on the island for a Haleakalā morning. Come down from the summit at eight, have breakfast in Kula, walk a lavender farm at ten and a winery at noon, and you have used a day the beach could not have improved on. And if the coast is hot, or windy, or you have snorkelled enough, upcountry is where Maui keeps its shade.