Create an elegant circular logo featuring a modified letter "O" on a white background. The letter should be composed of two smooth, curved lines that loop together at the top, leaving an opening at the bottom to represent flowing water. Employ a color gradient with the outer letter in a deeper blue and the interior water element in a lighter blue tone to resemble depth. Render the design in an abstract yet minimalist vector style, with an emphasis on fluidity of motion. The overall aesthetic should convey a sense of calmness and tranquility through the simple yet imaginative incorporation of water within the negative space of the letterform. Focus on achieving balance, symmetry and dimension while retaining a modern yet timeless visual impact suited for versatile applications.