That evening, we sailed on a mirror of water past Sugarloaf Mountain.

But in the twilight, it appeared as little more than a dark paper cutout.

As we headed out toward open sea, they vanished entirely.

Pair of photos in Buzios, Brazil, one showing a man with a diver, and one showing a hand holding a starfish

From left: Free diving near Búzios; a starfish from the sea near Búzios.Credit:Marta Tucci

First, though, I got an orientation to the 558-footVenturefrom expedition coordinator Claudio Schulze.

He led me to the ships Discovery Center, a theater designed for lectures and films.

WhileVenturecan accommodate 264 passengers, just 145 were on this cruise, accompanied by a 245-person crew.

Aerial view of zodiac boats on the Amazon river in Brazil

Exploring the Amazon by Zodiac, not far from Santarém.Marta Tucci

TheVenturehas 24 Zodiacs for offshore expeditions, and one of them zipped me to shore for a snorkeling adventure.

At the port, I boarded a wooden schooner for a sightseeing excursion.

As we got to chatting, I mentioned my interest in seeing bottlenose dolphins.

Infrared photo showing a woman on a cruise ship with stars in the sky above

A daytime infrared image shows the stars above the Venture.Marta Tucci

Olsen was quick with some advice: You have to be outside early.

So the next morning I was up at 5 a.m., and I wasnt alone.

Gathered at the bow were several ofVentures ornithologists and naturalists.

Pair of photos from Brazil, one showing a lagoon, and one showing a river dolphin

From left: Lagoa de Genipabu, a freshwater lagoon near Natal; a boto, or Amazon river dolphin, in the Rí­o Negro.Marta Tucci

Then, as we glided toward the port of Recife, the weather turned.

Hes our Hank Williams, Menezes said.

(Brazil abolished slavery in 1888.)

Pair of photos showing a schooner on the water in Brazil

From left: A schooner, near Búzios; guests snorkel just off the schooner.Marta Tucci

There were lighter moments, too.

During our amble around town, Menezes pointed out more than two dozen types of fruit-bearing trees.

From Recife, we pressed onward.

Pair of photos from the Seabourn Venture cruise ship, one showing a guest suite, and one showing a plate of food

From left: A Signature Suite on the Venture; prosciutto and fresh melon salad and pan-seared salmon in the Restaurant, aboard Seabourn Venture.Marta Tucci

I consumed many flat whites in the cafe just seconds away from my suite.

The ferociously athletic pursuit is a combination of martial arts, dance, and gymnastics.

Capoeira also involves clapping, chanting, and beats from the atabaque, a tall drum.

Pair of photos from Brazil, one showing brazil nuts, and one showing two capoeiristas

From left: Fresh Brazil nuts, a common sight along the Amazon; capoeira practitioners at a gym in Natal.Marta Tucci

Created by enslaved people from West Africa, it was later integrated with regional dances.

Today, its a window into the countrys diversity.

We have a very exciting day tomorrow!

Pair of photos from Brazil, one showing a traditional dish, and one showing a church near the water

From left: Moqueca, a classic seafood stew, with rice, beans, and farofa, in Natal; the basilica of Nossa Senhora do Carmo, in Olinda, Brazil, near the port of Recife.Marta Tucci

he exclaimed, before piercing our lofty expectations by running through a laundry list of misconceptions about the Amazon.

Rojas warned us about anticipating a parade of jaguars, anacondas, flowering jungles, and howler monkeys.

Its not just a river, he told me.

Pair of photos from Brazil, one showing colorful buliding facades, and one showing a cruise ship with purple flowers in the foreground

From left: Colonial-style façades in Olinda; Seabourn Venture near Búzios.Marta Tucci

The Amazon, Rojas concluded, is like love.

Its a concept so big you cannot possibly explain it.

The next morning, I was back at the bow ofVenture,alongside Rojas and many others.

Pair of photos from Brazil, one showing guide books and binoculars, and one showing a man looking at the camera while using binoculars

From left: Expedition essentials, including required reading, aboard Seabourn Venture; bird-watching near the mouth of the Amazon River.Marta Tucci

To our southeast was Marajo, an island about the size of Switzerland.

I paused to fathom the astonishing vastness.

Its home to almost a third of all the plant and animal species.

Pair of photos from the Seabourn venture, one showing an on-board lounge, and one showing a crew member portrait

From left: The Bow Lounge, on Deck 6 of the Seabourn Venture; Anthony Ubarte, a safety officer and one member of the 245-person Venture crew.Marta Tucci

I thought back to a trip, not long ago, when Id sailed up the Nile.

Its banks always seemed within reach.

During the rainy season, parts of the Amazon can be a staggering 30 miles wide.

The Seabourn Venture cruise ship on the water in Brazil

Seabourn Venture on the Amazon River near Santarém.Marta Tucci

Guests were asked to limit their use of water by taking shorter showers.

Against an easy current, we kayaked past water hyacinths and watched jacana birds trot across giant lily pads.

The good thing about expedition ships is that people bring their curiosity, a member ofVentures team said.

I had learned so much from the expedition crew.

I had sampled sticky fruits I never even knew existed.

And deep in the Amazon, I felt the granular and the grand merge once again.

14-day Amazon Delta trips on theSeabourn Venturefrom $5,999 per person, all-inclusive.