Begin by preparing the blue gelatin according to the package instructions, typically involving dissolving it in boiling water. Stir until fully dissolved, then add cold water. Let cool for 15-20 minutes.

Crush the vanilla cookies into fine crumbs resembling soft sand, using a food processor or a zip-top bag with a rolling pin. Set aside.

Layer the crushed vanilla cookies in mason jars, about one inch high, creating the 'sand' base.

Pour the slightly cooled blue gelatin over the cookie layer, filling the jars three-quarters full.

Allow the gelatin to set in the refrigerator for approximately 30 minutes before adding gummy sea creatures.

Cover with plastic wrap and chill for at least 2 hours until fully set.

Add a dollop of dairy whipped cream on top before serving for a frothy ocean wave effect, omitting if preferred.