linguistic:translation, structural:reformatting
European summiting attempts

James Cook 's third voyage was the first to make landfall on Hawaiʻi island, in 1778, and following adventures along the North American west coast, Cook returned to the island in 1779. On his second visit John Ledyard, a corporal of the Royal Marines aboard HMS Resolution, proposed and received approval for an expedition to the summit Mauna Loa to learn "about that part of the island, particularly the peak, the tip of which is generally covered with snow, and had excited great curiosity." Using a compass, Ledyard and small group of ships' mates and native attendants attempted to make a direct course for the summit. However, on the second day of traveling the route became steeper, rougher, and blocked by "impenetrable thickets," and the group was forced to abandon their attempt and return to Kealakekua Bay, reckoning they had "penetrated 24 miles and we suppose within 11 miles of the peak"; in reality, Mokuʻāweoweo lies only 32 km (20 mi) east of the bay, a severe overestimation on Ledyard's part. Another of Cook's men, Lieutenant James King, estimated the peak to be at least 5,600 m (18,373 ft) high based on its snow line.

The next attempt to summit Mauna Loa was an expedition led by Archibald Menzies, a botanist and naturalist on the 1793 Vancouver Expedition. In February of that year Menzies, two ships' mates, and a small group of native Hawaiian attendants attempted a direct course for the summit from Kealakekua Bay, making it 26 km (16 mi) inland by their reckoning (an overestimation) before they were turned away by the thickness of the forest. On a second visit by the expedition to the island in January of the next year Menzies was placed in charge of exploring the island interior, and after traversing the flanks of Hualālai he and his party arrived at the high plateau separating the two volcanoes. Menzies decided to make a second attempt (above the objections of the accompanying island chief), but again his progress was arrested by unassailable thickets.

Menzies made a third attempt to summit Mauna Loa in February 1794. This time the botanist consulted King Kamehameha I for advice and learned that he could take canoes to the south and follow the ʻAinapō Trail, not knowing of its existence beforehand. Significantly better prepared, Menzies, Lieutenant Joseph Baker and Midshipman George McKenzie of Discovery, and a servant (most likely Jonathan Ewins, listed on the ship's muster as "Botanist's L't") reached the summit, which Menzies estimated to be 4,156 m (13,635 ft) high with the aid of a barometer (consistent with a modern value of 4,169 m, 13,678 ft). He was surprised to find heavy snow and morning temperatures of −3 °C (27 °F), and was unable to compare the heights of Mauna Loa and Kea but correctly supposed the latter to be taller based on its larger snow cap. The feat of summitting Mauna Loa was not to be repeated for forty years.

The Hawaiian Islands were the site of fervent missionary work, with the first group of missionaries arrived at Honolulu in 1820 and the second in 1823. Some of these missionaries left for Hawaiʻi island, and spent ten weeks traveling around it, preaching at local villages and climbing Kilauea, from which one of its members, William Ellis, observed Mauna Loa with the aid of a telescope and ascertained it and Kea to be "perhaps 15,000 to 16,000 feet above the level of the sea"; they did not, however, attempt to climb the volcano itself. It is sometimes reported that the missionary Joseph Goodrich reached the summit around this time, but he never claimed this himself, though he did summit Mauna Kea and describe Mokuʻāweoweo with the aid of another telescope.

The next successful ascent was made on January 29, 1834, by the Scottish botanist David Douglas, who also reached the summit caldera using the ʻAinapō Trail. By the time Douglas reached the summit the environment had put him under extreme duress, but he nonetheless stayed overnight to make measurements of the summit caldera's proportions and record barometric data on its height, both now known to be wildly inaccurate. Douglas collected biological samples on the way both up and down, and after a difficult and distressing descent began collating his samples; he planned to return to England, but instead several months later his body was discovered mysteriously crushed in a pit beside a dead wild boar

Isidor Löwenstern successfully climbed Mauna Loa in February 1839, only the third successful climb in 60 years.