The fire took place mid-morning on Bank Holiday Monday (29 May) with smoke being across the city.
No injuries were reported in the incident, with the occupants of the boat said to have stepped to safety before the fire took serious hold.
The cause of the fire is still being investigated.
A spokesperson for Swansea Council said: “We were alerted to a fire on a boat in the Pocket’s Wharf area of the Marina at 11.43am and staff were immediately deployed
“Two people were on board the boat and thankfully were able to step off uninjured. No other boat owners were on the pontoons at the time.
“The fire service responded quickly and the fire was extinguished. It had spread to a neighbouring boat and several others have suffered heat damage.
“Fuel absorbent booms have been deployed as a precaution and we are working to repair the pontoon so that other owners can access their boats to inspect for damage.
“The cause of the fire is being investigated.”
(Image: Ang Davies)
A spokesman for Mid and West Wales Fire and Rescue Service said: “At 11.43am on Monday, May 29th, the Swansea Central, Swansea West and Tumble crews responded to an incident at Swansea Marina.
“Two small boats located in the water were totally destroyed by fire, four other boats were affected by the heat. Crews extinguished the fire using two 45mm jets, thermal imaging camera and life jackets and cordons were established for public safety.
“The scene was handed over to the Swansea Marina manager, the Coastguard and harbour master were also in attendance.
“Crews left the scene at 1.14pm.”
(Lead image: Ang Davies)
