Yes it is submersible. This is your best choice because the pump has a very low profile but still comes with a 3/8 outlet adapter which is the most common tubing used with the old S10. This pump is not as tall but with the addition of the 3/8 adapter is very close. Every fountain or other piece of equipment where S10's are used will usually work with the RO320S as well. We accept returns up to 30 days after purchase and we do have other pumps that we sometimes use depending on the installation.