I got asked this question last week. Trimble supported the Ohmex Echosounder in SCS900 when I was responsible for the products at Trimble, and it was dropped in Siteworks initially, however they added back that functionality last year (2019). The video below shows how to do this.
This allows you to survey below the water in river, lake, shallow water marine environments using SPS GPS products combined with the Sonarmite Echosounder.
This really is a good solution if you only do this type of work occasionally, and the Sonarmite echosounder is a great piece of equipment - Click Here for the Ohmex website
If you place an order for this with your dealer - tell them Rockpile Solutions sent you over!