I copied the very useful discussion below from the AGLCA list. Crystal River is one of the southermost of the Big Bend River, found north of Homosassa River. Note the data about shallow water at Twin River Marina. I join with Captain Alan below in recommeding that cruisers continue upstream to Pete’s Pier Marina, or try anchoring in Kings Bay.

We were told there was enough water to come into Twin River Marina, however, boats sit on the bottom at low tide. Any boats with a draft over 3.0. will have a problem. I always ask about draft and channel clearance, and was told no problem. That has not been the case.

We draw just 2’10” maybe 3′ when fully loaded and would concur that spots can be a bit shallow. We commented a number of times going in, that big boats would have a hard time getting into Twin Rivers Marina. Even at our depth we stirred up some mud. Take care as it sure is worth the effort to be able to swim with those Manatees. For me one of the high lites of our whole trip.
Clare

Continue three miles further up Crystal River and you will find a deeper alternative to Twin Rivers Marina, viz., Pete’s Pier Marina or Kings Bay anchorage. We were there this time last year and arranged for a pontoon tour round Kings Bay to see the manatee.
Alan Lloyd
Great Loop Navigation Notes

We’re docked at Pete’s Pier Marina. Good to be off the Gulf while the next system moves through. We planned on staying just one night, heading to Clearwater this morning, but the system is moving through faster than the forecast indicated last night. The staff here are great. This marina is in walking distance to town, had a wonderful meal last night at Cody’s. Enterprise is right around the corner too.
Denny and Karen
Another Option

Click Here To View the Western Florida Cruisers’ Net Marina Directory Listing For Twin Rivers Marina

Click Here To View the Western Florida Cruisers’ Net Marina Directory Listing For Petes Pier – Kings Bay Marine