Contemplating the grandeur of the ocean is also an opportunity to reflect on the goodness of God the Creator, Pope Francis said in a message for a day of prayer for the care of creation.

“It is our duty to thank the Creator for the impressive and marvelous gift of the great waters and all that they contain, and to praise him for covering the earth with the ocean,” the pope wrote in a message Sept. 1.

“To ponder the immense open seas and their incessant movement can also represent an opportunity to turn our thoughts to God, who constantly accompanies his creation, guiding its course and sustaining its existence.”

The pope’s message was sent on the occasion of the fourth annual World Day of Prayer for the Care of Creation, which he established in 2015, shortly after the release of his encyclical on the environment, Laudato si.

The day takes place each year on Sept. 1. Francis’ decision to institute the day is in keeping with themes expressed in the encyclical and is seen as a sign of unity with the Orthodox Church, which established Sept. 1 as a day to celebrate creation in 1989.

In 2017, the pope’s letter was a joint message with Patriarch Bartholomew I of Constantinople, the head of the Eastern Orthodox Church.

The theme of this year’s day of prayer is “Water, particularly in two aspects: respect for water as a precious element and access to ‘water as a human right.’” Water, Francis wrote, “is a very simple and precious element,” yet access to it is difficult, or even impossible, for many people.

“In an evocative image, the beginning of the book of Genesis states that, in the beginning, the spirit of the Creator ‘swept over the face of the waters,’” he said. “On this Day of Prayer, I wish first to thank the Lord for the gift of our common home and for all those men and women of good will committed to protecting it.”

Today, care for the “treasure” of water is an inescapable “duty and genuine challenge,” he said, noting the need for cooperation of men and women of good will in assisting God’s ongoing work of creation.

Francis explained that Christians have a responsibility to care for the world’s seas and oceans, and to keep them from being littered “by endless fields of floating plastic,” which he called an “emergency” needing to be fought with active commitment.

“We need to pray as if everything depended on God’s providence, and work as if everything depended on us,” he said.

He also invoked prayers that water would be a sign of encounter between people, not separation. He also prayed for fisherman and sailors; politicians engaged in the issues of climate change and migration; and those who safeguard maritime ecosystems.

“Finally, let us be concerned for the younger generation and pray for them, that they may grow in knowledge and respect for our common home and in the desire to care for the essential good of water, for the benefit of all,” he stated.

“It is my prayerful hope,” he concluded, “that Christian communities may contribute more and more concretely to help everyone to enjoy this indispensable resource, in respectful care for the gifts received from the Creator, and in particular rivers, seas and oceans.”