angle Battery battery-powered charged charging daytime energy energy-efficient garden garden-light inexpensive internal-rechargeable-battery lamp led light light-emitting-diode lighting plastic portable power solar solar-panel solar-powered spike-light stationary steel technology top beacon blue coast danger green Ital powered rock sea warning water guidance guide Jetty location marker navigation passage route transport travel anchored buoy data-collecting-buoy dissolved-oxygen electronic-data-transfer estuarine estuary fish-kill-mitigation floating-device fresh-water improving-understanding monitoring-buoys moored oxygen-levels salinity salt-water scientific-advisory tidal tide water-quality water-quality-management direction lighthouse marine maritime moder ocean.sailing panel