WikipediaKaumana Cave is a lava tube created by a 1881 lava flow from Mauna Loa. The tube has been surveyed at 2.026 miles (2197 m) long making it the 57th longest lava tube in the world. The cave is located on the island of Hawaiʻi near the city of Hilo. A collapsed skylight provides easy access to two of...
https://en.wikipedia.org/wiki/Kaumana_Cave
Or hikes by the two volcanos - plenty of trails between the two volcanos in the middle of the island. Take plenty of water.
Also, this one is nice...
I did most of these hikes...
Hiking on the Big Island: The Big Island of Hawaii offers a diverse range of hiking trails, from easy strolls to challenging treks, showcasing its unique landscapes and ecosystems. Some popular hikes include:
Kilauea Iki: A pit crater in Volcanoes National Park with a lava lake, offering stunning views and a unique hiking experience.
Pololu Valley: A scenic hike on the Kohala Coast, featuring erosional valleys and expansive views of the ocean.
Papakolea Green Sand Beach: A rare green sand beach, accessible via a hike along the southern coast.
Akaka Falls State Park: A short, family-friendly hike to one of the most beautiful waterfalls in Hawaii.
Mauna Loa: A challenging hike to the summit of the largest volcano on Earth, offering breathtaking views and a chance to explore unique ecosystems.
Kiholo Bay: A picturesque hike to a calm, turquoise bay, perfect for swimming and snorkeling.
Waimanu Valley: A remote and challenging hike, requiring substantial effort, but offering stunning views and a chance to explore a unique valley.
The Puna trail is mostly covered (sun protection), but there are wet/muddy spots on the trail. It ends near the historic Shipman house and the lagoon/bay has freezing cold water bubbling up from the mountains far away. Very nice hike/bay.
https://www.alltrails.com/trail/hawaii/hawaii/puna-trail?u=i&sh=rmjkav
Food:
Hilo: Kenichi (Japanese food)
We liked the Tacos Jalisco food truck. It's not glamorous, but it's good food.
We made it our mission to try as many shave ice places as possible whenever we go to Hawaii. So far, Mountain Magic was our favorite shave ice (Oahu). We also liked Hawaiian Brain Freeze (Hilo) and Ululani (Hilo).