Which piece of specialist equipment is NOT typically used in swimming?

Surfboards are primarily associated with surfing, which is a different water sport rather than traditional swimming. While they can be used in water, they do not facilitate swimming in the same way that the other equipment items do. Snorkels, buoyancy aids, and rubber rings are all specialized equipment designed to enhance the swimming experience. Snorkels allow swimmers to breathe while their faces are submerged, buoyancy aids help individuals stay afloat, and rubber rings provide support and fun for swimmers, particularly beginners or those in need of assistance. Therefore, identifying surfboards as the correct answer is accurate as they do not fit the context of swimming specifically.