The search criteria allowed is a function of the service provider, in this case Trulia. To search for 'waterfront' homes, in the search criteria area at the top of the search page, there is a button that says 'More Filters'. After clicking this button, you will see an area to the left of the expanded screen that says 'Keywords'. Just type in the word 'Waterfront' into the keyword search and it will narrow your search (using the other criteria you've entered) to show you waterfront homes!
I hope this helps, but if you have more questions or need further help finding what you are looking for, send me a message at email@example.com.