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Underwater and sea themed cakes are particularly great choices for a summer themed cake, but they remain popular year round and are suitable for all ages.  In this quick cake decorating tutorial we'll show you how to create a stunning yet simple buttercream under the sea effect.  Perfect for mermaid themed birthday cakes, pirate party cakes, sailing celebration cakes and all manor of occasions.  Let's dive in... (ok, forgive me, I couldn't resist...)

What we used:

All the ingredients for an underwater themed cake

Step 1:

Make up a basic buttercream (ratio of 500:250).  (If you're interested to learn more about different types of buttercream and tips on how to make it, also check out this article!)

Weigh out 450g, 200g & 100g into separate bowls. Add the Peacock gel to the 450g bowl, Green to 200g and the White dust to 100g. Add a little gel at a time, mixing well until desired colour is achieved. 

Step 2:

Using the 6" palette knife, cover the whole cake in blue buttercream. The beauty of this type of theme is you can be as neat or rough as you like to reflect the desired mood of your sea!  It's an occasion where messy really can improve the end result!

Cake covered in blue buttercream

Step 3:

Using the 4" palette knife, apply the green buttercream along the bottom edge of the cake. Move your knife in an ‘S’ movement to help create a deep sea look.

Cake covered in next layer of buttercream

Step 4:

Finish with random strikes of white buttercream across the cake and there you have it - a wonderful sea of buttercream!

Cake covered in white buttercream

From here, the possibilities are endless! Add your favourite characters on top of your cake or how about creating a pirate themed celebration cake or mermaid cake?!  Tell us about your favourite sea themes below and if you try this technique, how did you get on?

Finished underwater themed cake



It looks Amazing I am definitely going to make this.

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