Wear or carry one or more of the following: Aquamarine, Beryl, Coral, Pearls, Holed Stones (particularly beneficial during storms at sea)
Bladderwrack is a seaweed that also goes by the name "sea spirit." (Not to be confused with agar agar.) Carry bladderwrack for protection when traveling over the water, whether by boat or plane.
Paint eyes on your boat so it can see where it is going.
St Mary's beans float across the seas from the tropics of the Westren hemisphere to the shores of the Orkney and Hebrides islands. Carrying one of these beans allegedly protects you from drowning.
Sprinkle dulse onto the waters to calm the sea.
Create a cap from hazel leaves and twigs for luck and safety while journeying at sea. Wear it if you will, but at least keep it with you.
To calm a storm at sea, or at least to provide individual safety, toss a pack of playing cards into the waves as Christopher Columbus once did.
Rosemary derives its name from rosmarinus, which means "dew of the sea." Carry it with you for safe travel in the ocean.
Hang garlic from boats to protect against a malevolent enchantment that might cause a shipwreck. If it isn't your boat, carry garlic with you.
Carry ti leaves on your journey. According to Hawaiian tradition, ti plant leaves protect vessels from harm and individuals from drowning.
Before the start of your journey, make an offering of tobacco to water water spirits and request safe passage. (This should be the actual botanical, not the contents of a cigarette.)
Carry wormwood on your journey over water. It allegedly offers magical protection from sea serpents and other creatures of the deep.
From: The Element Encyclopedia of 5000 Spells