Evanstonian Tom Carmichael has a fondness for the Chicago River because two milestones took place there: his first job interview and his marriage proposal.

“One worked out for me and the other didn’t,” laughed Mr. Carmichael, who now is one of Chicago Architecture Foundation’s river docents, volunteer guides on the river cruises alongside Chicago’s magnificent storyline.

“But I’m not saying which one’s which,” he added.

Eight other Evanston residents besides Mr. Carmichael are river docents. CAF utilizes about 450 docents, around 85 of them the “river docents” who guide the cruises.

“You can’t be dumb and be a docent,” said Rebecca Dixon, another docent from Evanston. “You’re ambassadors to the city and the area.”

Ms. Dixon had been interested in Chicago’s architectural heritage since she came to the area in 1983; she was giving her own landmark tours to visiting friends long before she was affiliated with CAF.

CAF docent training is stringent for a volunteer organization. All docents must undergo around three months of intensive study, with river docents’ studies lasting two months more.

Each cruise depends on numerous factors working in concert. “You have to be both a narrator and a crowd manager for 90 minutes, with no notes” Mr. Carmichael said.

But getting used to expecting the unexpected is one of a docent’s most pertinent job requirements. Anything can happen, and a docent must be ready to vamp.

“I got mooned once by some charming lasses,” said Ms. Davis, laughing.

Occasionally the river fails to cooperate completely.

“Many of us are or were teachers, and we like to play a crowd,” Mr. Carmichael said. “How often do you get the chance to give someone the best 90 minutes of their life?” he asked.