HSwMS Capella (T123) was a Swedish Navy Spica-class, torpedo-armed, fast attack craft (FAC).

The hull was made of steel, unlike some other contemporary designs which used plywood.

Although the boat had a relatively small hull and displacement, this provided a stable platform.

The Bridge and Operations Room were located at the rolling and stamping centre of the ship which further improved stability for the crew especially in high seas.

The boats were fitted with an NBC support system where the hull could be closed down in the event of having to operate in a nuclear fall-out area.