HNoMS Uthaug (S304) may refer to one of the following submarines of the Royal Norwegian Navy:
- HNoMS Uthaug (S304) (Kobben class), a Kobben-class submarine, commissioned in 1965; transferred to the Royal Danish Navy in 1989; renamed HDMS Sælen (S323)
- HNoMS Uthaug (S304) (Ula class), an Ula-class submarine, commissioned in 1991 and in active service