[1] Following this experience, they realized that to bypass the mountains of Costa Rica and the jungles of Panama they would need an amphibious vehicle in order to go by sea when they couldn't get through on land.

[2] Before the Schreiders could set off on another venture, they needed to raise money, so before finishing the jeep repairs they left for a two-year job at an air force base in Anchorage, Alaska.

[3] The Schreiders started their journey from Circle on June 21, 1954, arriving in California a couple of weeks later where they continued to work on the rehabilitation of the amphibious jeep.

[8] Navigating this tangle of trees, vines, boulders and mud, with the help of local people and their machetes, they finally reached the wall of mountains in Costa Rica that had blocked them four years earlier.

[9] La Tortuga proved to be seaworthy and they entered the Pacific on four occasions and survived four terrifying days in rough ocean water.

In parting, the admiral said that if they made it through the Caribbean to South America and Tierra del Fuego, he would recommend Frank to the Explorers Club.

Initially, these isolated people thought La Tortuga was a sea monster, but upon seeing the Schreiders and Dinah, they treated them with great hospitality.

[21][22] Afterwards, often with no roads to speak of, they traversed Bolivia to Chile, where La Tortuga sailed 50 miles across three interconnected lakes to get to Argentina and proceed to its southern tip.

[25][26][27][28][29][30] Fortuitously, a few days later, an officer of the Argentine Navy invited them, along with the battered Tortuga, to board a freighter for Buenos Aires, and eventually they arrived back home in California on April 9, 1956.

[31][32][33][34][35][36] Frank started writing about their travels while on board the ship and within a few months he completed their book 20,000 Miles South, which Doubleday published in 1957.

[45] At one of the first such events at Constitution Hall in Washington DC, Dr. Melville Bell Grosvenor approached them and asked them to work for National Geographic.

After their presentation at Constitution Hall, the nationally syndicated columnist, Ed Koterba wrote that "all other travel settings on the surface of this earth must be anti-climactic after the Schreider voyage" and that their amphibious jeep, "La Tortuga," should be placed in the Smithsonian Museum "right along with the Spirit of St. Louis and other dramatic symbols of ‘famous firsts.’"[46] Shortly after the Schreiders successfully completed their journey, Admiral Milton Miles of the US Navy recommended Frank to the Explorers Club, and on September 17, 1956 Frank was inducted as a member.

[48] Also, Dr. Melville Bell Grosvenor met them in India during their journey and described their adventures in considerable detail in his report "A message from your Society’s President.

"[49] After India, the Schreiders set off on their next expedition, this time, to Indonesia – for a challenging and dangerous 5,000-mile journey by land and sea from Sumatra to East Timor.

After their Indonesian expedition, National Geographic hired the Schreiders as full-time staff, and sent them to explore the Great Rift Valley through Africa by Land Rover.

[61] Their journey is referred to in several sections of Linda Street's book Veils and Daggers: A Century of National Geographic's Representation of the Arab World.

Their new German shepherd, Balthazar, accompanied the couple as they managed to navigate and map the entire Amazon River, concluding that it was longer than the Nile.

Highly enthused, they returned home to the National Geographic headquarters in Washington DC, but they were abruptly told by the head cartographer that he didn't want to see their maps and documents, adding, "Everyone knows the Nile is the longest river in the world" – and they were curtly dismissed.

This led to further disillusionment with National Geographic, causing the Schreiders to resign from the company in 1970, the year that their book Exploring the Amazon was published.

[71] It was further authenticated by Lowell Thomas in his April 20, 1970 broadcast: "Helen and Frank Schreider are the first to trace the mighty Amazon from its headwaters to its mouth .

Later he joined the U.S. Foreign Service and was sent to Mexico City to work for the United States Information Agency, where he was the editor of Saber, their Spanish-language magazine.

Eventually, women were also accepted but it wasn't until 2015 – 59 years later – that Helen finally caught up with Frank, becoming a Fellow National, not just a Member of the Explorers Club.

[82] Ms. Schuster had arranged for a retired geography professor, John Ryan, and a film producer, Anna Darrah, to conduct an interview with Helen as the basis for her article.

[83][84] More than fifty years after the Schreiders' amphibious jeep travels, a group of adventurers led by Richard Coe had planned to travel from London to Sydney, Australia in a large U.S. military amphibious vehicle (to be called Tortuga III) that would have retraced the exact Asia route of the Schreider journey in their Tortuga II.