Since most kayaks are extremely light and have a shallow draft (depth), they tend to be very stable when empty. Their stability decreases as loads are added.
Human occupants present the most challenge, not only due to weight but also because of the potential for imbalance.
Shifting loads can also lead to capsizing. Before launching, it is important to secure loose equipment, especially heavy items.
To minimize instability, it is important to keep occupants and all equipment as low as possible and centered in the craft. In most cases, standing up or leaning over the gunwale is all but impossible.
Kayak Capsizing – Causes, Prevention, Recovery