Anywhere else in the world, stringy clumps of yellow-green plant matter would not be newsworthy—

But out here, far out in the middle of the Atlantic, after days and days of vivid empty blue depths, something floating on the surface of the water becomes an event.

“Sargasso!” declares the expedition leader, and we all look down in awe. Out here in the borderless blue of the open sea, Sargasso weed is the closest thing to a road sign announcing that we have arrived—that we have traveled out of the regular Atlantic and entered this gyre of water, slowly spinning its clockwise currents.

The Sargasso Sea is one of the clearest parts of the sea, with amazing visibility and the abundant plant life for which it gets its name. Beyond the clumps of seaweed, we crossed paths with several beautiful marine mammals, including a massive pod of speedy dolphins that leapt skyward, sometimes suspended for seconds in the air, as if flying. Dozens of splashes surrounded the ship, as if we had entered a feeding frenzy of joyful dolphins. We are used to this now—it seems we have seen dolphins almost every day of this expedition, and close-up, too.

There are moments when I crouch down on the bow, staring straight down in the water and it feels like, if I wanted to, I could reach down and touch the dolphins that dance hypnotically in the rush of water around our ship.

Our life at sea remains peaceful, full of sunlight and blue ocean, with lectures and tea time, classes, and phenomenal dinners. We have accepted that this is our life for the weeks to come, and we are content with this knowledge. Traveling at a dozen or so knots feels nice, gently pushing across the blue miles of the map, inching closer and closer to the equator.