One day in Maui
 

Aloha. We are joining Dad and stepmom on a cruise from LA to Hawaii. Dad is not well and this is his bucket list trip. We are sailing on Dec.1, 2018.

I've looked over the excursions offered by the ship and we prefer to rent a car in Maui and drive around for the day. I've been to Maui before but it was in 1985 when I was only 3 years old. (Yeah right, I'm really that young) OK so I was older than 3 but it was still a long time ago. I remember the drive to Hana was very long so we probably won't be able to do that in just a day. What do you recommend? So far I'm thinking of the Plantation tour and Io Park. I remember the Haleakala drive and I'm walking the fence on whether or not that's worth doing again. If you can recommend a public beach with snorkeling that will be appreciated, as well as any other ideas you have.

Mahalo

If your dock is Lahaina, explore the old town there, drive to the north and visit Black Rock or similar for snorkeling (and farther north that way is a lovely drive).
if dock is Kahului, go to Kamaloe Beach Parks (ok, if not great, snorkeling) or past Kihei to turtle town near Makena (lots of beaches and spots to snorkle, but some are easier parking and access than others). Wailuku near Kahului has some nice historic places (from ancient heiaus to missionary-era houses and church), and nearby Iao Valley State Park is lush, lovely, and has an almost palpable historic vibe.

Remember that all beaches are public; you could always pay (through the nose) to park and walk through hotel grounds or lobby to access beaches, if public parking gets tricky.

Thanks Sylvia, good info. Our port is Kahului but we have about 12 hours in Maui so we could see all of the places you mentioned.

I believe that the snorkeling reef between Kamaole II and Kamaole III is excellent. I have been there many times.
These beach parks are good places to hang out. Scenic with nice amenities and dining across the street.

That's a good amount of time: if you drive as far as La Perouse Bay, the scenery is very interesting (go as far as the most recent lava flows). If you explore the oceanfront route, there's historic stone Keawala'i church right on the ocean (it hollars for photos) on Makena Road.
A drive upcountry from Kahului to the Maui Winery for the tour/tasting goes through a few climate zones and is very pretty.

I really enjoyed driving around UpCountry a lot, visiting a protea farm and the winery and other places then stopping in Paia for lunch and watching the windsurfers at Hookipa. That should not take up a whole 10 hours though.

I love Haleakala so that would be way high on my list (not for sunrise or sunset or even hiking, just the drive up and an easy look around at the main viewpoints to me was the highlight of Maui).

I did enjoy walking Lahaina and that would be fun just for an easy stop, lots of restaurants choices, small central area again for ease of access. And interesting history that town.

12 hours is a long time! I would drive through Paia and upcountry to Haleakala (agree with suze, it doesn't have to be for sunrise or sunset). I'd stop in Makawao. Maybe go to the Iao needle (I don't know, in 6 trips to Maui, I've never been, despite great intentions). Maybe take the first part of the Road to Hana. I'd poke around Lahaina. I'd walk along the beach path in Kaanapali. All of which will be punctuated by a couple of meals - lunch a and dinner.

Many great ideas, thank you all.

I'd also vote for a trip up and down Haleakela and then Lahaina for dinner. The drive to Lahaina is one of the great coast drives and you get great views of Maui and the surrounding islands. I'd pass on the Hana road -- not enough time with one day. We've snorkeled around Black Rock and also in Kapalua on the west side. You would be able to see some fish at the Kamaole beaches and access in your time frame might be easier, but the snorkeling might be better elsewhere.