Advanced　light　sources　in　the　blue-green　band　are　crucial　for　underwater　wireless　optical　communication　(UWOC)　systems.　Vertical-external-cavity　surface-emitting　lasers　(VECSELs)　can　produce　high　output　power　and　good　beam　quality,　making　them　suitable　for　UWOC.　This　paper　presents　a　108　m　distance　UWOC　based　on　a　100　mW　490　nm　blue　VECSEL　and　an　acousto-optic　modulator　(AOM).　The　high-quality　beam,　which　is　near　diffraction-limited,　undergoes　relatively　small　optical　attenuation　when　using　a　conventional　avalanche　photodiode　(APD)　as　the　detector　and　employing　64-pulse　position　modulation　(PPM).　At　the　time-slot　frequency　of　50　MHz,　the　bit　error　rate　(BER)　of　the　UWOC　was　2.7　×　10−5.　This　is　the　first　reported　AOM-based　UWOC　system　with　a　transmission　distance　over　100　m.　The　estimated　maximum　transmission　distance　may　be　improved　to　about　180　m　by　fully　utilizing　the　detection　accuracy　of　the　APD　according　to　the　measured　attenuation　coefficient　of　the　blue　VECSEL　used.　This　type　of　UWOC　system,　composed　of　a　high-beam-quality　light　source　and　a　conventional　detector,　make　it　more　closely　suited　to　practical　applications.　©　2024　by　the　authors.