Yes, some corrosion resistant bearings are suitable for underwater use. Ceramic bearings, those made from zirconium dioxide or silicon nitride, can operate when fully submerged. In fact, ceramic bearings are completely unaffected by seawater and can be used even when they are permanently underwater and with higher loads.
316 grade stainless steel bearings are another option but are not considered underwater ball bearings. While they exhibit good corrosion resistance, they are only effective if temporarily submerged. 316 stainless steel It is less effective when permanently submerged unless there is a regular high rate flow of water over the bearing which allows a regular supply of oxygen to the bearing surfaces.
For complete underwater corrosion resistance, you may also require ball bearing relubrication to provide a more suitable oil or grease. SMB Bearings has several waterproof greases which we can use to re-lubricate customer supplied bearings. Find out more here.
For more information on ceramic bearings, contact the team on +44 (0) 1993 842 555 or sales@smbbearings.com.