A young jack fish hides inside a jellyfish, demonstrating their unique symbiotic relationship. Anilao, Philippines. (Photo: Katherine Lu) 
A group of lemon sharks breaks the surface at sunset. The Bahamas. (Photo: Katherine Lu)
A tiger shark swims across a healthy reef, teeming with fish. The hook in its mouth serves as a stark reminder of their vulnerability in the face of human impact. The Bahamas. (Photo: Katherine Lu)
A mother humpback whale teaches its young calf to swim in a warm and calm lagoon. Mo’orea, French Polynesia. (Photo: Katherine Lu)
A nurse shark swims through a large school of jackfish. The Bahamas. (Photo: Katherine Lu)
A juvenile wunderpus octopus shows off its translucent body. Anilao, Philippines. (Photo: Katherine Lu)
A paper nautilus leaves a cloud of ink behind after being startled by the photographer’s presence. Anilao, Philippines. (Photo: Katherine Lu)
A whale shark swims alongside a diver in a remote area of Indonesia, providing a sense of scale. Indonesia. (Photo: Katherine Lu)
Numerous jellyfish have been isolated in this saltwater lake without predators for thousands of years. Over time, they have lost their ability to sting. Raja Ampat, Indonesia. (Photo: Katherine Lu)
A young jack fish hides inside a jellyfish, demonstrating their unique symbiotic relationship. Anilao, Philippines. (Photo: Katherine Lu)