I see a craft store trip in the near future. (Bottles are aquapod water bottles). For an ocean bottle use half water & half baby oil with a few drops of food coloring, for a slow motion bottle use light corn syrup.
Toddler Sensory Activity: Soapy Jars filled up some old peanut butter jars halfway with water. More upcycling!] Add a few drops of food coloring. And a squirt of dish soap. Hand to your toddler for the day