Among the small pleasures of exploring post-sunset hangs for this column each week is the possibility that maybe, just maybe, I'll experience a moment or two that'll remind me how cool my job is.

Walking into a dimly lit cellar jazz club to local jazz diva Azure McCall caressing "Fly Me to the Moon" as if it were written just for her certainly qualifies.

Discovering a vocalist as crazy gifted and versatile as David Swanson, who accompanied McCall on piano, matched her vocalese, and stole any solo turn given him? Ditto.

Deep Blue claimed both moments last Friday. But the 3-month-old wannabe upscale Waikiki supper club still came off as a cool concept sunk by lackluster execution.

The supper-club idea is simple enough: live entertainment, a meal and, if one is fortunate, good service and some well-thought-out atmosphere. Deep Blue gets two of these right.

McCall — the club's resident vocalist, playing five nights a week — is terrific wherever she sings. And she didn't disappoint at Deep Blue, owning exquisite, lived-in re-imaginings of Chaka Khan's "Sweet Thing," Aretha Franklin's "Baby I Love You" and standards like "Smoke Gets in Your Eyes."

Offstage, McCall talked story with the crowd, shimmied with servers when Swanson dug into a deliciously funky cover of Jeffrey Osborne's "Stay With Me Tonight," and even busted some fly moves with a couple working the dance floor.

Service was excellent — from the attentive staff who served us to a doorman who warned us DJs would be taking over the room once McCall finished her set to some dude who pulled out my chair when I got up to make a phone call.

The not-so-good?

First, an under-the-sea decor theme carried a bit too far by too many things blue — blue overhead lighting, blue walls, blue candles — and none-too-subtle scuba-view murals that seemed more makeshift tossed-in than well-planned or elegant.

The decor certainly didn't match the so-so sophistication of a pricey Asian-fusion tapas menu. And our order of bacon-wrapped shrimp ($13.50) was unforgivably bland, our spicy tuna roll ($12.50 for a full order) OK but miniscule.

Bathed in unrelenting blue light, both items possessed all the queasy visual appeal of a meal at the home of a Dr. Seuss character.

Still, with Swanson bringing on the brazen vocal cojones needed to meld James Brown's "It's a Man's Man's Man's World" with Alicia Keys' "Fallin' " and pulling it all off effortlessly, I wasn't about to leave until he and McCall called it a night 'round 10:30.

The early-evening crowd — a mixed-age, mostly casually dressed gathering of tourists and a few locals — must have felt the same. Most, including yours truly, cleared out only after Swanson's last call — once, twice, "Three Times a Lady" — making way for DJed nu-school R&B until 2 a.m.

Among my small pleasures right afterward: Zippy's.

Reach Derek Paiva at dpaiva@honoluluadvertiser.com.