How to make a Sea Geyser

In our October issue of Good Taste, Chef Bruce Robertson of The Flagship schools us in the world of culinary seaweed. While we were there, he showed us another way to cook with aquatic weeds—by creating an oceanic pressure cooker with floating sea bamboo bulb. It’s a trick locals have been doing for years; and will blow your guests out of the water at the next braai.

Here's a step-by-step guide on how to make a sea geyser, plus a recipe from Neptune himself aka Chef Bruce Robertson

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You will need a very fresh sea bamboo bulb (kelp), knife, garden hose clamps and something to bung the Sea Geyser up, either wine corks or pebbles.

Cut off the frilly fronds on the circumference of the bulb.

Before you follow the rest of the steps - add what you'll be cooking (recipe below). Cut a smaller section of the stem, and insert it into the opening of the Sea Geyser.

Pop in your wine cork, then tighten with garden hose clamps.

The Flagship ‘Sea Geyser!’ by Chef Bruce Robertson

The below recipe may vary depending on the interior size, chamber capacity of the floating sea bamboo bulb. 


1 very fresh harvested sea bamboo (kelp) bulb, with an approximate 

interior capacity of 1litre

100ml court bouillon

50g unsalted butter

2 bay leaves

150g mussel meat, freshly blanched

150g fresh line fish, diced

150g crayfish meat, diced

100g Freshly picked sea lettuce

1 Tbsp ‘instant’ chicken noodle soup 

½ lemon, quartered

2 sprigs curly parsley


Trim the head leaves off the bulb and cut the stem close enough to the bulb to create a 3cm diameter opening and rinse with fresh cold water. Holding the bulb upright “stuff” the bulb with the geyser ingredients and top it up with the court bouillon. Plug the opening with either a beach pebble or a bung made from the remaining stem of the sea bamboo shoot. Tighten with a garden hose clamp. Place the whole “filled” bulb onto a hot braai grid and cook on a very hot flame/each side for 20 minutes. Once cooked, carefully remove bulb and lid remembering that the liquid inside is hot with added pressure. Best served with plain steamed rice and homemade mayonnaise. 

Court bouillon recipe

This makes 500ml/half a litre


1 leek 

1 carrot

1 celery stalk 

2 shallots 

½ fennel bulb 

1 sprig lemon thyme

1 sprig lemon verbena

½ tsp.-dried tarragon

parsley stalks

4 white pepper corns

Zest of 1 lemon

100ml dry white wine

500 ml cold water or enough to cover


Rinse and coarsely chop all vegetables and together with the herbs place in a large pot, cover with cold water and bring to the boil. Add white pepper corns, lemon zest and white wine, then simmer for 45 minutes. Pass through a sieve, discard all solids and store the liquid, ready to use.

Swim on over to The Flagship to find out more about Chef Bruce's daily seafood extravaganza