Love reading through this! I feel like you've written other poems with the shore and ocean personified or the main theme. It's always refreshing to have dialogue in a piece as well, and I do see a life lesson in this. A lesson on time even.

"I know, the tides from oceans are rising higher.
Soon, tsunamis will have us breathing under water"

Said the shorelines."

- I like how you make the shorelines a collective voice, instead of the singular shoreline. It makes me think of a unified land, of this foreshadowing to what will come. That they have knowledge and know the cycles of time. Also, should "Said" be "said"?

"Not long ago, I was but a shallow land:
the shoreline ground where lovers walked;
Holding hands, kissing under the moonlight.
But then came the tide, the water rose
pass my land..."

- Two suggestions here. I don't think "Holding" needs to be capitalized since it's after the semi-colon, even though it can stand alone as a thought? Not sure but up to you. Also, should "pass" be "past"? here

I like how you give the ocean floor this voice of wisdom; I almost feel humbled by it and like its age and experience can teach others.

"I was filled with depth.
Not the depth of the most profound
parts of the Ocean,
But with the depth to comprehend,
that now, my waters were enough
for a child to swim in them.

And now, with the passing of time,
my waters have risen more than enough
for people to dive in them."

- Your transitions here are neat and give this poem the depth I crave. You make that distinction that it's not simply the depth of the waters as in measurement, but an understanding. The image of a child swimming in them is gentle, then to the image of people diving in them speaks to me of how we mature, and how we go from riding the waves to making our own so to speak.

"Though I still feel like what I am,
a shoreline like you, both, are.

Nothing changed."

- Beautiful and sort of nostalgic (or contemplative?) ending. The ocean is making the connection the shoreline, still seeing itself in them, recognizing we may generally remain the same though others travel in and out of our lives.

Wonderful read!

The shore and the ocean though joined together each one have its own beauty and story. I like how you have given them character and voice, bringing out feelings which we humans have and share. An interesting write filled with emotions...nicely penned!

Nicely penned with great depth.