In various embodiments, a surgical instrument for operation in an aqueous environment is provided. In at least one embodiment, the surgical instrument may include a hollow sheath, a blade disposed at least partially within the hollow sheath and extending through an opening in the sheath, and at least one ultrasonic transducer operably coupled to the blade. The blade may include a polygonal cross-sectional shape and the tip may project away from the sheath's longitudinal axis. In another embodiment, the surgical instrument may include a blade with suction disposed therethrough and at least one ultrasonic transducer operably coupled to the blade. The blade may include a cutting edge that is positioned over a blade opening. Also, the cutting edge may project away from the blade's longitudinal axis.