A source of water, either natural or man-made, can be a visual image for sense meditation. You can search for photographs of different states of water to use.
Using eyes, which is a sense organ, means you’re using sense meditation. The link leads to an article which was written earlier, about using eyesight in sense meditation. Please read this as it is an introduction.
You can create your own visual image for your sense of sight. Use simple images for meditation. For example, if you’re going to create the image of water, look for a transparent glass or clear plastic bottle. Fill it half way with water. Place this source of water in front of you before you begin meditation.
Look at the water inside the glass, You can also look at the glass of water as a whole entity. Try to use your other senses to relate to the water. Do you smell the water? Can you imagine the water touching your lips? Can you taste the water? Can you hear the sound of water gushing down your throat? Imagine the cool, quenching water as you drink it. This glass of water is for you to enjoy. Isn’t it a marvelous liquid?
You might be tired looking at the glass of water and thinking about it. Its time to slowly bring yourself out of meditation. Take a deep breathe. Stretch yourself. Are you ready to return to your world?