to create a vbo I use this function:

    public void loadVBO(){
        vboID = GL15.glGenBuffers();
        GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboID);
        GL15.glBufferData(GL15.GL_ARRAY_BUFFER, buf, GL15.GL_STATIC_DRAW);
        // Put the position coordinates in attribute list 0

        GL20.glVertexAttribPointer(0, 4, GL11.GL_FLOAT,
        false,4*4+4*4+4*4+2*4 , 0);
        // Put the color components in attribute list 1
        GL20.glVertexAttribPointer(1, 4, GL11.GL_FLOAT,
        false,4*4+4*4+4*4+2*4 , 4*4);
        GL20.glVertexAttribPointer(2, 4, GL11.GL_FLOAT,
        false,4*4+4*4+4*4+2*4 , 4*4+4*4);
        // Put the texture coordinates in attribute list 2
        GL20.glVertexAttribPointer(3, 4, GL11.GL_FLOAT,
        false,4*4+4*4+4*4+2*4 , 4*4+4*4+4*4);

        GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
    }

to display a vbo I use this function:

    public void displayVBO(){
            GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboID);
            GL20.glEnableVertexAttribArray(0);
            GL20.glEnableVertexAttribArray(1);
            GL20.glEnableVertexAttribArray(2);
            GL20.glEnableVertexAttribArray(3);
            GL11.glDrawArrays(GL_TRIANGLES, 0, buf.capacity());
            GL20.glDisableVertexAttribArray(0);
            GL20.glDisableVertexAttribArray(1);
            GL20.glDisableVertexAttribArray(2);
            GL20.glDisableVertexAttribArray(3);
            GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
    }

So when I call map.loadVBO() and then ocean.loadVBO(), I think the second call overwrite the first vbo I don't know how ...

When I call map.display() and ocean.display(), I have the ocean draw 2 times ....

Thanks.