You could describe your painting like this:
"This piece captures the lively atmosphere of a fun beach day at Yanchep Lagoon, where the beauty of the ocean meets an unexpected thrill. The artwork showcases the vibrant blue water, golden sands, and the joyful energy of beachgoers enjoying the day. In the midst of the scene, a shark swims close by, adding a touch of suspense and reminding us of the untamed nature that lies beneath the surface. The contrast between the carefree beach atmosphere and the presence of the shark brings an element of surprise, highlighting the delicate balance between humans and marine life."