The Thesen Islands Marina development is situated on the southern coast of South Africa, in the heart of the internationally renowned Garden Route, the marina is set in the ecologically sensitive context of the Knysna River Estuary.


Thesen Island was previously owned by the Thesen family (early settlers in Knysna) and used as a timber processing plant for more than 80 years.  In 1974 the island was sold to Barloworld and the factory was enlarged.  But by the early 90’s there was growing community concern about the environmental and industrial pollution, noise and traffic caused by the factory’s activities and in 1991 CMAI, a Multidisciplinary Urban Design, Architectural and Land Planning design firm, proposed a complete redevelopment of the island.

Initial planning took the interdisciplinary team of consultants four years to complete.  Apart from having to re-zone the area from industrial to residential, the islands’ sensitive estuarine location had to be addressed.  After a further four years of research and further planning, approval was finally granted in 1999 by the relevant authorities - but with more than 100 strict and complex Conditions of Approval. At the time, the planning and design process was viewed as the most comprehensive and detailed  application ever done in South Africa.


The New Urbanist principle of Traditional Neighbourhood Design underpins the design of the development.  The layout incorporates a variety of stand sizes in order to appeal to a spectrum of potential buyers - setting the basis for an authentic community. Home owners range from people of retirement age, to families with small children, to young professionals.


New Urbanist liveable neighbourhoods - in both a rural and urban setting - are hamlets or villages built to reduce dependency on cars, provide easy access to public and commercial amenities, increase community interactivity, increase cost-effectiveness of services and provide a simplified but higher quality of lifestyle.  Emphasis is placed on the creation of quality public spaces.

As a result, one of the delights and arguably one of the most successful aspects of Thesen Islands is its cohesive system of open spaces.  A network of tree lined and pedestrian friendly streets link the neighbourhood amenities such as the commercial village centre – called “Harbour Town”, complete with  communal mooring facilities, open space and sports facilities which are favoured by the entire community.


The key site-specific factors which played a critical role in the evolution of the design and lead to the exceptional nature of the project are as follows;


  • Avoidance of salt marsh areas as ‘no-go’ areas during construction.  Nearly 10% of the original island was covered with salt marshes.  In the limited areas where salt marsh was to be disturbed it was carefully lifted from its position, temporarily cared for in a nursery and transplanted to specially prepared locations on the island.

  • Thesen Islands was originally one island of approximately 90 ha.  The decision was taken to divide it into 19 smaller islands.  The cut from the canals was used raise the natural ground level of the original island by 1,8 meters to mitigate the risk of flooding and susceptibility to sea level rise. Today, all the floor levels on Thesen Island is 3 Meters above mean sea level which is higher than most levels of downtown Knysna.

  • Retention and adaptive re-use of significant existing factory buildings.  These buildings today form the “structure” or back bone of Harbour Town, as anchors for public spaces and squares and as elements of maritime heritage

  • Retention of much of the existing seawall for use as an eco-walk

  • Rehabilitation of contaminated land.  Some 300 cubic metres of toxic material and contaminated soil was taken to a toxic dump site.  A 1ha square piece  of ground which was contaminated to a depth of 3 metres was capped with a layer of sodium bentonite, covered with 2 metres of top soil and sealed , on which was built the parking area and tennis courts

  • The huge amount of wood  waste material generated during the rehabilitation of the island was re-cycled , composted and re-used wherever possible. There was a total of 60 000 cubic metres of timber off-cuts and sawdust which was fine milled, injected with nitrogen and bacteria and turned into compost. Timber poles from the sheds were reused to edge retaining walls and create features such as the Maze, in the parkland.

  • Tests were made in 1999 to determine the best practical solution for the canal embankments. Timber, brick, concrete and stone gabion retaining walls were tested.  Gabions were chosen as the most cost effective and aesthetically pleasing canal edge treatment. It also complied with the stringent technical and environmental criteria stipulated.

  • One of the conditions of approval stipulated that as many elements as possible of the Thesen Islands development were to be designed to be as labour intensive as possible. The CMAI design team designed all the street lights and bollard lights, street furniture and trash receptacles with wood and steel. All of these were manufactured in Knysna by local artisans as were the rails on all 19 bridges spanning the canals and in the process created huge job opportunities. 

  • Stormwater management – with no direct runoff permitted into the lagoon, swales collect stormwater and allow it to slowly infiltrate back into the ground ….. no stormwater pipes were used .


Thesen Islanders can live life in tune with nature’s rhythms – they can “rise with sun, fish with tides and rest with the moon.” They can fish from their own private jetties, grow their own oysters or mussels in the nutrient-rich waters of the estuary, grow their own vegetables in the communal organic garden patches, harvest fruit from the island orchards or simply sit on a grassy berm watching the herons and black oyster catchers and other species of birds at work and play.


  • The biodiversity of the island has been enhanced. 22 ha of aquatic habitat has been added to the lagoon. The embankments of the canals provide a prime environment for marine organisms including the Knysna Seahorse. Since then various scientific papers have borne out  and justified the original design decision to use wire caged gabions which has now proven to be a fantastic habitat for the Knysna Sea Horse.    There is 13 ha of parkland in which bird life is thriving in the naturalistic planting and the man-made nesting boxes of the wetland area.

  • The parkland also contains the Island plant nursery, chipping green, tennis and squash courts, clubhouse, maze, children’s playground, orchard and communal vegetable patch.  Together with the communal beach and its ablution block this form the hub of the Thesen Islands Community Open Space.

Today, Thesen Islands is viewed and acclaimed by many people as one of the premier Marinas and Waterfront developments in the world.

The project, and the design team has won numerous local International Awards and has been awarded Blue Flag status for years and years.

All of this signifies and strengthen CMAI’s beliefs and Philosophy that major developments such as Thesen Islands, if planned and designed correctly, can successfully be developed and implemented hand in hand with important conservation areas, even in the most sensitive of environmentally sensitive estuaries such as the Knysna Lagoon.

Based on the above successes, CMAI Architects will continue its core business philosophy  of 

“creating better places for people to live”