You can easily see Lanai island across the channel from Kihei and Wailea. Smaller, slower paced and easily accessible; you can experience a different island life in an easy day trip.
There are different tour boats that can get you there, mostly out of Lahaina, with BBQ's , snorkeling and helpful staff. I haven't been on any of them so I won't make any suggestions. There is also a ferry which goes back and forth between Lahaina and Lanai. It's the most cost effective but it is a ferry so you'll be getting a ride without a helpful guide. If you choose the ferry pack a lunch because the only place to eat lunch along the beach on the island is Four Seasons, which is wonderful, but extremely expensive.
However you get there you will pull into the small harbor of Manele which is a short walk to a wonderful snorkeling beach, Hulopoe Beach. There are other island beaches: Shipwreck Beach and Polihua Beach. Both require a 4 wheel drive or a heavy hike. Polihua is the most beautiful but can have rip currents so venture out with great caution.
The most surprising fact I found is Lanai is a primarily a private island. 97% of the island's 140 miles is owned by Larry Ellison, the founder of Oracle Software Company. I've often wonder what type of person owned an ocean front home in Maui. It never crossed my mind somebody owned one of the Hawaiian Islands.
The landscape you see today isn't what Lanai would naturally look like without man's hand. In 1778, one of the Chiefs from the Big Island tried to expand his holdings by taking over Maui. His attacked failed and in retaliation he killed all 6,000 inhabitants of Lanai and burnt down the island. Barren Lanai was dry and arid until the arrival of ranch manager George Munro in 1911.
Munro discovered that Lanai’s lone Norfolk pine was pulling moisture straight out of the clouds. (Planted in 1878, this tree still stands in front of the Lodge at Koele) Since clouds would frequently gather in the uplands, but rarely drop any rain, Munro ordered that pine trees be planted to pull water out of the sky. Hundreds of Cook Island pines were imported and planted to cover the island. Each pine tree can collect up to 200 gallons a day and is changing the island.
Not only is Lanai the only privately owned Hawaiian island but it has one of the most unique sites you will see in all of Hawaii.
Lanai's Cat Sanctuary is home to some 600 cats. Visitors are welcomed to come scratch a few ears at the outdoor enclosure created by two transplanted artists. They were surprised by the over abundance of feral cats on the island and they wanted to do something to care and protect both the cats and the native birds which were becoming cat food. Thus the birth of the Cat Sanctuary.
Part time Maui resident sharing my Kihei condo with guests when I'm staying in my mainland home.