Marine sand-fly ash-based geopolymers offer a sustainable alternative for soil stabilization in marine regions. However, achieving optimal strength remains challenging due to alkali activator ratio variations and curing conditions. This study investigates the influence of sodium silicate (Na2SiO3) to sodium hydroxide (NaOH) ratios, temperatures, and duration of curing on the unconfined compressive strength (UCS) of marine sand-fly ash-geopolymer mixtures. Marine sand and fly ash-geopolymer were mixed in a ratio of 3:1. Geopolymer-fly ash was made with a ratio of fly ash to alkali activator of 65:35. The Alkali activators (sodium silicate and sodium hydroxide) were adjusted to different ratios 1:1; 1,5:1; and 2:1. The molarity of activator was fixed at 12 molars. The Sand-Fly ash-Geopolymer specimens were molded and cured under controlled conditions. Curing temperatures ranged from 26 °C, 30 oC and 50 °C. The UCS tests have been performed at ages 7, 14, and 28 days. The highest strength was observed when the activator ratio was 2:1. The UCS after seven days of curing was 1986.54, 2322.48, and 5844.70 kPa for curing at temperatures of 26, 30, and 50 °C, respectively. Higher curing temperatures accelerated strength development. The specimens that were treated at a temperature of 50 °C had the most significant level of strength. The combined effects of the activator ratio and curing conditions were significant. Balancing alkali activator ratios and selecting appropriate curing temperatures are critical for achieving optimal strength in marine sand-fly ash-geopolymer stabilization. This research contributes valuable insights for sustainable coastal infrastructure development.