Marine species guide
Whale shark
The whale shark is the world’s largest fish and a bucket-list encounter for divers. Learn how to recognise individuals, where sightings concentrate, and how to share the water respectfully.
Identification features
Whale sharks have a broad flattened head, a huge terminal mouth, and a checkerboard of pale spots and stripes on a dark grey-brown body. Three prominent ridges run along each flank. Size commonly ranges from 4–12 m for animals divers meet; exceptional individuals grow larger.
Spot patterns behind the gills are unique and used in global photo-ID. The caudal fin is crescent-shaped with a larger upper lobe. Unlike predatory sharks, they are filter feeders on plankton and small fish.
Similar large animals include basking sharks (colder water, different mouth) and manta rays (winged disc, no dorsal fin of shark type). If you only see a pale belly from below, wait for a side view of the spot lattice before logging an ID.
- Checkerboard spot-and-stripe pattern
- Terminal mouth at the front of the head
- Flank ridges along the body
- Filter feeder, not a hunting shark
Habitat and behaviour
Whale sharks roam tropical and warm-temperate oceans, often near upwellings, reef passes and fish-spawning aggregations. They may feed at the surface with the mouth open or cruise mid-water.
Surface feeding days can bring animals into snorkel depth; scuba encounters often happen on leisurely parallel courses at 5–20 m. They may ignore divers if approaches are calm, or veer away from noisy chase behaviour.
Where and when to see them
Egypt’s Red Sea has seasonal sightings linked to productivity. The Maldives offers seasonal windows around atolls. In Mexico’s Yucatán region, related seasonal aggregations draw snorkellers (typically not deep scuba inside cenotes themselves—coastal aggregation zones differ from cave diving).
Always check local codes of conduct: many regions limit swimmers per animal and ban touching or scooter use.
Dive tips
Position yourself ahead and to the side of the travel path; let the shark choose proximity. Do not ride, grab or block. Exhaust bubbles aimed at the head can turn an animal.
Photograph the flank spot field for ID research when possible. Afterward, compare notes in Scuba Steve’s fish identification app and link the sighting to your dive-site research.
Frequently asked questions
Do whale sharks bite?
They are filter feeders with tiny teeth and pose little bite risk. The main hazards are boat traffic and diver crowding.
How big do they get?
Adults often span several metres; divers commonly meet animals around 4–10 m, with rare larger individuals.
Best photo angle for ID?
A clear side view of the spot pattern behind the gills is most useful for photo-ID catalogues.