The new reserve, named "Hermandad" (Brotherhood), expands the protected waters by 60,000 square kilometers (23,166 square miles). It builds upon the existing Galapagos Marine Reserve, which already protects about 133,000 square kilometers of water from extractive activities.
"There are places that shape human history, and today we have the honor of being in one of those places," Lasso said while on a ship in the bay of Puerto Ayora, a town in the Galapagos.
"These islands teach us something about ourselves," Lasso said. "What if we didn't set ourselves up as masters over this Earth, but as its protectors?"
Lasso first announced the expansion in November in Glasgow, on the occasion of the COP26 climate summit. The project was in exchange for a reduction in Ecuador's international debt.
"The seas are great regulators of the global climate," Lasso said. "Taking care of them is not naive idealism," he added. "It is a vital necessity."
Why is the expansion important?
The new marine area will eventually link Ecuador's Galapagos Islands with Panama's Coiba islands, Colombia's Malpelo and Costa Rica's Coco.
Advocates say the passage can protect the migration routes of rare species.
Matt Rand, who leads marine habitat conservation efforts for The Pew Charitable Trusts, said: "Safeguarding the pathway between the linked biodiversity hot spots of the Galapagos and Costa Rica's Cocos Island helps to preserve this spectacular array of marine life.
"Ecuador's new protections recognize the critical importance of connectivity in effectively protecting highly migratory species such as sea turtles, sharks and whales," Rand said.
A UNESCO World Natural Heritage Site
Since 1978, the archipelago has been a UNESCO World Natural Heritage Site known for its unique flora and fauna.
It's thought to be home to more than 2,900 marine species, including rare ones such as marine iguanas and Galapagos finches.
In 1835, English naturalist Charles Darwin spent time on the islands, which helped inspire his theory of evolution.
The reserve was created in 1998. The expansion creates 198,000 square kilometers of protected marine area.