Any underwater image showing natural animal behavior. This includes (but is not limited to) feeding, hunting, fighting, courtship, mating, yawning, and activity at cleaning stations.

Any image with a focus on marine or freshwater environment and conservation. The subject matter must address a marine or freshwater-related environmental issue, whether it be considered positive or negative. The goal of images in this category is to convey a real-world message.

Any image of a pelagic macro subject captured on a blackwater or bonfire dive. While blackwater images are generally taken at night and are characterized by a black background, images shot during the day, as long as the background is black, are also acceptable.

Any image captured with a smartphone. Both underwater and split shots are permitted, as is the use of dome ports and attachments such as wet lenses, and artificial lighting.

Any portfolio comprising six images. The portfolio may be made up of any six images (no more, no fewer), but entrants are encouraged to choose images either following a particular theme (e.g., species, location, color) or demonstrating a range of skills or interests (e.g., behaviors, environments, techniques). Both underwater and split images are permitted. For detailed instructions on submitting a portfolio entry, please see the competition Rules & Guidelines.

Images of two types are allowed in this category: drone images and over-under images. The former are photos captured with a drone that depicts our “ocean planet”, where the main subject is a natural water body (sea, lakes, rivers, streams, wetlands, etc.). The latter are photos where the lower portion is underwater and the upper portion is above water, demonstrating the connection between land and water on our “ocean planet.” Over-unders (aka splits or half-and-halfs) must have been captured in a single frame in camera.

Images of two types are allowed in this category: underwater model images and artworks. The former are images of a model (or models) photographed underwater, whether in a natural water body such as the ocean or in a controlled environment like a swimming pool. The latter are any artistic works depicting or inspired by the ocean or other natural water body. Artworks may be created through two-dimensional media such as drawing, painting and printmaking, or mixed media; digital drawing and painting tools may also be used. Artworks must be photographed for submission.

Any film, five minutes or less in duration, where at least 50 percent of the footage is shot underwater. The remaining footage may be captured on land or from the air, including via drones.