In　tropical　islands,　calcareous　sand　with　poor　engineering　properties　usually　needs　to　be　treated　before　it　can　be　used　as　building　materials.　Considering　the　scarcity　of　freshwater　in　these　areas,　this　study　proposes　seawater-based　enzyme　induced　carbonate　precipitation　(EICP)　technology　to　enhance　the　properties　of　calcareous　sand.　It　is　to　induce　calcium　carbonate　crystals　to　bond　calcareous　sand　particles　together　using　the　seawater-based　crude　soybean　enzyme　and　cementation　solution　(i.e.,　urea　and　calcium　chloride).　In　this　study,　the　crude　soybean　urease　extraction　test　was　firstly　carried　out　using　seawater　and　it　was　also　investigated　what　components　of　seawater　had　a　greater　effect　on　the　soybean　urease　extraction.　Afterwards,　the　solution　test　was　conducted　to　explore　the　ability　of　the　extracted　urease　in　inducing　calcium　carbonate　through　analyzing　the　variation　of　concentration　of　calcium　ions　and　pH　of　the　solution.　Finally,　the　biocementation　effect　of　EICP　treated　calcareous　sand　using　the　seawater　extracted　urease　solution　was　evaluated　by　the　unconfined　compressive　strength　(quc)　and　microscopic　analysis.　Test　results　show　that　the　turbidity　of　the　seawater-extracted　soybean　urease　solution　can　be　reduced　by　66.7%　compared　to　that　of　deionised　water　extracted　urease,　with　only　a　slight　reduction　in　urease　activity.　Among　all　the　components　of　seawater,　NaCl,　MgCl2,　CaCl2,　NaHCO3　and　KBr　can　significantly　reduce　the　turbidity　of　soybean　urease　solution.　The　lower　turbidity　can　effectively　avoid　bioclogging　and　contribute　to　the　homogeneity　of　the　EICP-treated　calcareous　sands,　and　thus　improve　the　biomineralization　efficiency　and　strength　enhancement.　Seawater-based　EICP　treatment　will　be　a　great　promising　technology　in　freshwater-scarce　tropical　islands,　because　it　can　directly　use　seawater　for　biomineralization　treatment　of　calcareous　sand,　and　meanwhile　effectively　avoid　local　clogging　of　biocementation.　©　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature　2024.