There are so many things to do on the Big Island — zip-lining, hiking, volcano tours, snorkeling and diving, to name a few. The largest of the Hawaiian Islands packs more than enough outdoor adventures to fill a week, month or lifetime. But if you've got limited time on your Hawaiian vacation, here's how we recommend you spend it.

On the northeast coast, a 30-minute drive from Hilo, is Akaka Falls State Park, one of the easiest and most affordable ways to add some waterfalls to your Hawaiian vacation. A paved path guides guests to a first fall that drops 100 feet, then onward to the namesake Akaka Falls, spilling 442 feet down a wall covered in rainforest greenery.

For that thrill of action on the line, the Big Island delivers. This outpost destination attracts tons of big game fish, meaning that travelers devoting just a day to offshore fishing stand excellent odds of pulling in mahi-mahi, wahoo and skipjack tuna. Plus, on occasion, anglers score a yellowfin tuna, short-nosed spearfish or blue marlin.

As a bonus, many charters encounter whales and dolphins while on the water. One operator we love is TOPSHAPE Kona Sports Fishing, whose 43-foot Cabo yacht comes with AC in the main cabin, and Wi-fi onboard, allowing you to post the victory shot long before you return to harbor.

Skyline Eco-Adventures Big Island Zip-line Tours gets our vote for the best canopy experience on the Big Island. Throughout the three-hour, nine-line course, you'll fly over rainforests and river canyons, and right past waterfalls. Oh, and during the halfway break, you'll be treated to local tropical produce, such as strawberry guavas.

This trail is one of the most popular things to do in Big Island, and for good reason. The largest valley of Kohala Mountain offers a short trail — 7½ miles combined trip taking three hours there and back — with an elevation drop of 975 feet down to a black-sand beach, and then back up.

Make the trek and be rewarded with nonstop greenery, including banana and avocado trees, horses wandering through taro fields and waterfalls spilling over mountainsides.

The Big Island is one of a handful of destinations where snorkeling offers the chance to reliably see manta rays — and on Kona, these fish with wingspans of up to 22 feet can be encountered just yards from shore.

At several locations, including the Sheraton Kona Resort and Spa at Keauhou Bay, massive underwater lights shine into the darkness to attract clouds of plankton, which, in turn, lure in mantas, sometimes by the dozens, to come feed.

The best part is that no experience is required, although participants do need to be comfortable in the water at night.

Hawaii Volcanoes National Park is hands-down one of the best things to do on the Big Island, and one of the most popular attractions to visit. Stop first at Kilauea Visitor Center for up-to-the-minute information on lava flows — which conditions change daily — and get guidance on the best viewing spots and hikes to check out the action. (Note that the eruption in 2018 means there is not active lava flow in the park, as of press time.)

For a fun, faster-paced tour, consider a guided bike tour with Volcano Bike Tours. Because the park is huge, with attractions spread out, biking is an excellent use of time, whether you choose the half- or full-day adventure. Or opt to drive the Chain of Craters Road, which weaves through the park's otherworldly landscapes and ends where the lava rock meets the ocean.

To helicopter tour Big Island, check out Paradise Helicopters, operating out of the Kona Airport. We love all 10 of the tours they offer. Several offer the unique experience of possibly flying overtop red lava at Kilauea, the world's most active volcano.

The real show-stopper is the 2-hour sunset tour, with aerial views of the magma lake of Halema’uma’u Crater, plus the green Kohala mountains — all set against a fiery sky.

With Umauma Falls' Rappel and River Experience, sporty types get the thrill of scaling 250 feet down a waterfall into a natural pool. Clad in wetsuits and PFDs, guests can continue splashing through the Umauma River, sliding down natural waterslides and under more waterfalls.

Here's why it's worth the drive to Mauna Kea: This mountaintop rises above the cloud line at 9,000 feet. It's also one of the only places in the world where folks can drive from sea level to 14,000 feet in less than two hours. Note that a car with four-wheel drive is absolutely necessary, and if that sounds like too much of a hassle, book a tour with the pros, such as the one offered by Mauna Kea Summit Adventures.

Their tour gets you to the top, then offers hot dinner and parkas as night temperatures drop, darkness falls and you stay for stargazing through the operator’s powerful telescopes.

What to do in Big Island November through early May? Humpback whales populate the Pacific off the Big Island, choosing these waters as a safe place for mating and calving, as well as raising their young. Morning tours offer the best odds of sightings, with five encounters per hour on average in January and February.

Guests have the option of a more relaxing experience aboard a sailing catamaran, but we prefer the powerboat tours as speed allows groups to cover more real estate, increasing the number of encounters.

We like Captain Dan McSweeney's Whale Watching Adventures for their boat, and for the fact that they work in conjunction with whale researchers from the Wild Whales Research Foundation.