Each hike page on this website includes a short discussion about gear. When a hike indicates that all you need is standard gear, what I mean is the Ten Essentials below. While gear choices are an inherently personal decision, I decided to include some suggestions borne of experience.
The Ten Essentials:
These items have become a part of American backcountry lore. Here is my take on the essential ten with a few additions on the standards:
Map: Carry an embellished map of your route in at least 1:24,000 resolution and maps of the surrounding area in at least 1:100,000 resolution should you get lost. Maps, of course, are useless if you don't know how to read them.
Compass: Carry a well-constructed compass. A compass is useless if you don't know how to use it. You do understand how to switch from true north to magnetic north, right? How to do intersection and resection?
Sunglasses / Sunscreen / Sun Protection: The tropical sun in Hawai'i is brutal. A broad-brimmed hat is always a part of my ten essentials here, as well as extra sunscreen that is applied liberally.
Extra Food: Carry more food than you'll think you will need.
Extra Water: Carry more water than you'll think you will need. Although the climate is humid, I find that I need to drink water in the same way as I do in a southwestern desert.
Extra Clothing: Especially in the higher elevation areas of the Big Island, carry warm clothing should you need to spend a night out. I almost always carry a rain jacket.
Light Source: I always carry a headlamp with fresh batteries and extra batteries.
First Aid Kit: My first aid kit is quite robust, but still only weighs less than two pounds. I'm always able to stop bleeding, treat cuts, burns, deal with trail maladies, treat shock, and keep a victim warm and dry overnight.
Fire Starter / Overnight Kit: I carry matches and a lighter with a chemical firestarter. I also carry a lightweight reflective blanket for every member of my party.
Knife: I carry a sharp pocket knife and a multi-tool
Recommendations for Big Island Gear:
Boots: I recommend bringing Gore-Tex lined, sturdy, high-top hiking boots for the Big Island. Several of the hikes on this website cross murderous ʻaʻā lava that will chew up a pair of running shoes in less than a mile. Other hikes traverse rocky, wet, muddy trails. I rarely find a situation where I regret wearing my boots unless I know I'll be hiking on a well-traveled trail.
Dry Bags: Nautical grade dry bags provide a great way to waterproof essential gear like cameras, video gear, cell phones, and car keys (those electronic car keys for rental cars are expensive and break if they get wet...). Look for a retailer that sells gear for sea sports or river kayakers. I carry an expensive camera, so I like to be able to know that I can go completely underwater as long as it's stowed in my dry bag.
Warm Clothing: If you intend to do much hiking on the big volcanoes or in Hawai'i Volcanoes National Park, you will need plenty of warm clothing. The summits of Mauna Kea and Mauna Loa are over 13,000 feet, so you'll need winter hats, gloves, coats, and other warm gear to attempt a summit climb safely. The National Park's entrance is at 4,000 feet and is rainy, cool, and humid. Expect cool, chilly nights.
River Sandals / Water Shoes: There are plenty of opportunities to use water shoes while hiking on the Big Island, whether for stream and river crossings or for beach hikes.
Lava Tube Gear: If you intend to descend lava tubes on your own, you need a helmet, gloves, and an appropriate light source. I recommend a standard rock climbing helmet because your greatest risk is banging your head or protecting against falling rock, which is what rock helmets are made for. Gloves aren't for warmth -- lava tubes are usually mild and humid -- they are to keep your skin oils out of the delicate lava tube environment. Bring bright light sources and triple backups and extra batteries. Running out of light in a lava tube would make a great horror movie premise.