Island Gardens Megayacht Marina Dredging

Island Gardens is one of the only marinas in North America designed specifically for super-yachts. Deep Harbour Marina accommodates 35 to 75 mega-yachts, superyachts, and “giga-yachts” within a range of 80 to 480 feet, the largest collection of slips for yachts of this size in South Florida. Publicly owned Watson Island, connected to the beach and downtown by the MacArthur Causeway, also offers a seaplane base and a heliport that provides a link to the Caribbean and nearby airports. The new marina has its own customs and immigration office. 

With 5,000 linear feet of slips, Island Gardens Deep Harbour can accommodate 50 of the largest superyachts in the world, stretching up to 550 feet with drafts of 18 to 21 feet deep.


  • Cashman’s scope of work included dredging of the Island Garden Harbor, located on the west side of Watson Island. 
  • Placement of dredge spoils was at two recipient mitigation sites: Seagrass and Sponge, located in Biscayne Bay just north of the Julia Tuttle Causeway. Dredged materials were used to create a manatee marine habitat area. 
  • Cashman had four material transport barges, ranging in size up to 139’ by 52’ traveling between the dredge site and mitigation sites daily for offloading of dredge spoils. Two push boats were used to transfer the barges between sites. 
  • The dredge and mitigation sites were enclosed by a steel turbidity pipe pile and curtain upon commencement of dredging. Floating yellow turbidity curtains were deployed along the pile lines to designate the three work areas.
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Flagstone Island Gardens, LLC.
$22 Million
September 2014 - February 2015