When I do these kinds of layouts, I don't go overboard with the embellishments. I keep things simple and pretty clean. The following layout was done in the 12x12 scrapbook size and the photos were arranged in a grid.
The background is made up of 3 different sheets of paper: full sheet of light blue textured cardstock, 8" by 12" sheet of medium blue textured cardstock and a small torn sheet (with uneven edges) sheet of printed blue "ocean words" themed scrapbooking paper. I layered them all together using a glue stick.
The photos were done in a grid style and matted onto white cardstock and then I trimmed the grid into a rectangular shape leaving a 3/16" border. I then inked around all 4 edges with medium blue ink. Each of the 4 photos are a different size width wise but the same size height wise. I then matted the white photo block onto medium blue cardstock, inked around the edges again. I decided to do some pen work and added handstitched lines around all 4 edges using a blue glitter pen. I think it added some interest to it. To the left of the bottom photo I placed a chipboard sea shell using glue dots.
I made my own title block using chipboard letters "BEACH" and placed them onto white cardstock. I used a 3-dimensional sticker of tropical fish right underneath it and then inked around all 4 edges. I then matted my title block onto medium blue textured cardstock.
I made my own journaling block from light blue, white and medium blue scrapbooking papers. I inked around all edges. I did the journaling in my own handwriting and accented the journaling block with a 3-dimensional chipboard piece of a cute star fish. I then did some more pen work around all outer edges of my layout using the blue glitter pen.