The Creature From the Black Lagoon (1954)

I've never been a great fan of this one, even though it's among the most popular and famous of the fifties creature features.  I wasn't sure what it was since first watching it as a kid - eventually I realized that I didn't like the studio set feel of this film for the bulk of the central act. It was supposed to take place in the Amazon somewhere, but most of the scenes just projected this 'smallness' to the locale.  But, besides that, I just found much of it to be dull. This may have something to do with the fact that much of it, by necessity, takes place underwater. There are a lot of underwater swimming scenes and it's all just quite slow - and these also have the feel of a Hollywood tank, not a wild river or lagoon.  
The film begins, for some reason, with one of those preambles about how the Earth was formed, in the biblical sense. It doesn't really fit the plot of the film, even though the main lead (Richard Carlson) waxes poetic about how life in the Amazon remains the same as it was in ancient times, including mythical stuff about rats the size of sheep.  The plot is jump-started by the finding of a claw-like fossil; an expedition financed by Richard Denning heads out to the spot.  Their short trip over there is juxtaposed with shots of a live claw-like arm coming out of the water, posing a sinister threat. Indeed, some creature then kills a couple of natives already at the location.  Though the members of the expedition (including Julia Adams as Carlson's girlfriend and Whit Bissell) are alarmed in finding their dead employees, they proceed further as if this happens all the time.
As already inferred, others have a much higher opinion of this effort than I do:

Creature followed many monster movie patterns before they became clichés, including telltale warning signs (in this case tracks and bubbles), and a grotesque beast in love with a beautiful woman. I wonder if there is a purposeful Frankenstein reference in the how the creature shambles on land with outstretched hands. The ship functions like a sort of haunted house, with a trapped group of humans getting picked off one by one. I was reminded of Alien from the claustrophobic haunted-house atmosphere, the reptilian beast whom we often see only in dark glimpses, and the infighting among the crew. There are many mesmerizing underwater sequences, some calm, some with action . But I also love the idea of the Black Lagoon - dark waters, mysterious, with some hidden menace lurking somewhere underneath. There is something primal in this idea of the Lurker Below.

Goldweber, David Elroy (2012-06-14). Claws & Saucers: Science Fiction, Horror, and Fantasy Film: A Complete Guide: 1902-1982 (Kindle Locations 15083-15095). David E. Goldweber. Kindle Edition.

There were 2 sequels: Revenge of the Creature (55) and The Creature Walks Among Us (56). BoG's Score: 5.5 out of 10
Trivia From the Black Lagoon:

The duo responsible for playing the gill-man go uncredited in the film, but they are swimmer Ricou Browning underwater and dancer Ben Chapman on land. Browning, according to Bill Warren, could hold his breath for a full five minutes. Chapman is interviewed in Attack of the Monster Movie Makers (Tom Weaver, 1994). For Joe Bob Briggs (and I suppose for many others), "Browning' s expert swimming is what gives the movie its poignancy."

Goldweber, David Elroy (2012-06-14). Claws & Saucers: Science Fiction, Horror, and Fantasy Film: A Complete Guide: 1902-1982 (Kindle Locations 15076-15082). David E. Goldweber. Kindle Edition.