Island on Marinus

TARDIS crew steps onto deceptively calm sands of the glass beach, where tidal pools hide corrosive acid that dissolves Susan's shoe in seconds. Torpedo-shaped submarines lie washed ashore nearby, one holding a frogman's corpse in a torn protective suit—evidence of the surrounding sea's deadly barrier against intruders. Ian dons oversized boots for safety while footprint trails lead toward a distant pyramid, blending serene allure with lethal unpredictability that sharpens the crew's caution and hints at hidden inhabitants.