Psyche was sent to the underworld to collect a portion of Persephone's beauty for Aphrodite. She gets directions to the underworld from a tower.

"You shall take two gold coins and two honeyed cakes, you shall see a drowning man, a donkey driver, and the 3 Fates. But do not be distracted. And most importantly, save the cakes for Cerberus."

First Psyche saw Charon and gave her two golden coins to him. Charon led her across the River Styx in his boat.

The second thing Psyche saw was a drowning man, he had tried to swim across the river and drowned, but she was not distracted. 

As Psyche approached land she saw the Gates of Hell, and Guarding the gates she saw the three headed dog, Cerberus. 

To distract Cerberus Psyche threw her two honeyed cakes at him, and hurried through the gates.

As Psyche walked through the Gates of hell she saw the 3 Judges sitting at their table. She knew that's not where she needed to go, so she went around them. 

To the right of the judges Psyche saw the Phlesthon River, she was not able to go farther so she ventured in the opposite way

As Psyche moved through the underworld she came to a forest of black poplars and sterile willow trees. This is the Grove of Persephone.