For myself, a Sea to Summit needs to actually start at the ocean where I can touch the water. So I needed to find a small beach near the bottom of the Chain of Craters road to start from because the bottom of this road just ends with 30-50 foot cliffs into the ocean. I began this run by hiking 1.8 miles across lava fields to this beach at 9 PM and starting my Garmin at 9:25 PM to begin the run. I then ran up over 14,210 feet over the next 54 miles to make it to the summit just under 20 hours later. This is a difficult route since once you cover the first 34 miles on paved road, getting to 6,700 feet, you then transition to the trail and then pure lava flows. And from this point on you have 19 miles of lava flows in a deserted lifeless desert to make it to the summit at 13,678 feet. But the fun ain't over yet. You then need to hike (since who wants to run anymore) your way down 6 miles and 3,000 feet of elevation loss on lava fields to get to your ride at the Mauna Loa Observatory. This last part is harder than it appears on paper when you consider the elevation and your fatigue levels.
I did this self-supported with water caches places along the 34-mile road. From that point on I needed to filter water at a cabin at 10,000 feet which would be the last I would get for the next 11 miles up and 6 miles down. This is by far the hardest Sea to Summit of any of our Big Island Volcanoes that I've done. It was an incredible adventure and I hope someday someone takes the gauntlet and gives it a try. It is one serious hill - haaa.
Trip report: https://www.lifeintraining.com/ultrarunning/trip-report-sea-to-summit-mauna-loa-from-near-chain-of-craters-road/