What are the most worthwhile things to do in Maui on a first visit?

Haleakala is two parks under one fee. The vehicle pass admits a private non-commercial vehicle of 14-passenger capacity or less and all its occupants to the Summit and Kipahulu districts for three days, and the same three-day validity applies to the $15 per-person rate for anyone arriving on foot or by bicycle — with visitors aged 16 and over each needing their own pass and under-16s admitted free. If your trip includes more than one park day beyond that window, the $55 annual pass, good for 12 months from purchase, is the better buy.

The summit is the headline. Pu'u 'Ula'ula, also called Red Hill, is the highest point on Maui and in the park at 10,023 feet (3,055 m), and its observation deck is enclosed against the wind with wrap-around windows. Paved and unpaved paths spread out from it. Day-time entry needs no reservation of any kind — only the pre-dawn sunrise window is rationed — which is why an afternoon ascent is the simplest way to reach the top of the island.

Kipahulu, on the far southeast coast, is the opposite proposition — sea-level, wet, and reached by a long drive around the island's east side rather than up its flank.

Offshore, the channels between Maui and its neighbors sit inside a federal marine sanctuary covering water shallower than about 600 feet around the main islands, which is the basis for the island's winter boat trips.

Upcountry, the agricultural slopes are a genuine destination in their own right. The county's Kula Agricultural Park is divided into 31 lots of 10 to 30 acres each, worked by 26 local producers — a working farm landscape at elevation rather than a visitor attraction, and the reason the Kula road feels like a different island from the resort coast.

A short network of paved and unpaved paths radiates from the summit observation deck, so the highest ground in the park is reachable without a hike. Kipahulu asks the opposite of a visitor: sea-level humidity and a long approach road around the island's eastern flank rather than a car park at the top.

Nothing about the summit requires a 3 a.m. start except the sunrise reservation rule itself. The Summit District is open to day-time entry without a booking, so a visitor who misses the reservation window has not missed the mountain — only the sunrise. Given that the drive climbs past 10,000 feet, a midday ascent is also the version that lets you see the road you are driving on.

• Summit in the afternoon — No reservation is needed outside the pre-dawn window, and the paths around the observation deck are short.
• Kipahulu as its own day — The coastal district is far enough from the summit that pairing them in one day wastes the three-day pass.
• Upcountry on the way — The county farm park at Kula sits on the slope between the resort coast and the mountain road.

Reaching 10,023 feet means thin, cold air at the top whatever the coastal forecast says, and altitude tells on visitors who drive up the day they fly in. The sunrise reservation system is driven by parking capacity at a handful of viewing areas, so that one experience is genuinely rationed while the rest of the day is not. The two districts are not connected by any road inside the park, so "visiting Haleakala" means two separate drives. The upcountry lots are leased working farms rather than a public attraction, so treat the Kula area as a landscape to drive through and the park as the place to walk.

The Maui when-to-visit question in this group explains the whale season and the sunrise reservation window, which together shape the timing of both districts.