A common attack on seals is a vertical ambush. A shark holds position in darker water below a seal near the surface, then drives upward in a single burst; the strike can carry it partly or fully clear of the water in a breach. After the first bite it may withdraw and wait, reducing the risk of injury from struggling prey.
Its senses are tuned for this. Great whites smell blood and body fluids at very low concentrations over distance, a specialized tapetum lucidum sharpens their low-light vision, and the ampullae of Lorenzini — gel-filled pores clustered on the snout — detect the faint electrical fields of a hidden animal's muscle and heart activity at close range.
The "lone killer" image is misleading. Great whites forage alone but gather at seasonal feeding sites, where a size-based dominance order keeps conflict from turning lethal: larger sharks and established residents outrank smaller newcomers, and disputes are usually settled with body language — parallel swimming, gaping jaws, and exaggerated tail beats — rather than combat. Many bites on surfboards and swimmers appear to be investigatory: lacking hands, a shark uses its mouth to test an unfamiliar object, and usually releases it once it registers that the target is not fat-rich prey.