I've never been diving, other than with a snorkel and I don't do that well anyway. A few strokes below the surface at best. So this is a poem that I totally made up, based on nothing at all.

There are a few common devices running through many of these five-finger exercises. 

The words often tumble out - almost a stream-of-consciousness device, image, or thought one after another. I have lots of descriptors (which often get updated  - "blue and gold and red" turns into "Cobalt and saffron and magenta", sometimes words are made up - "sandwards" doesn't exist in my dictionary, but it owes a lot to "landwards", which does. 

Alliteration may confound normal sentence structure: "touch of the tender, tranquil tidal transit" replaces "touch of the calm and gentle ocean current". The meaning is almost identical, but the latter sounds prosaic to me in both senses of the word.

There is a rhyme scheme that is relatively rigidly imposed, although it differs from poem to poem. 

It is not uncommon that having done such a scheme, I end with a shorter, unrhymed line.

There's an irregular rhythm - it's not a set meter like iambic pentameter, but nor does it read like prose.

And there are verses that run out of bounds, or else it's written as a single verse which ignores the rhyme scheme altogether.

In this poem, there are ten lines that rhyme A-B-C-D-E-A-B-C-D-E, followed by another six that go A-B-C-A-B-C. Then that unrhymed final line. I could break a verse at those first 5 lines - it finishes with the end of a sentence, and a shift of focus from the light to the water. After the next five lines, the focus shifts to the diver, but that focus starts to shift at the end of the previous line, with "towards the waiting". It just doesn't make sense to break it there, and to just break at the end of line five is visually unbalanced. The decision then was to leave it as a whole, and I still think that's the best option. In spite of three major focus points, the poem is one.