There is a whole BUNCH of military landing craft developed during WWII...
Here is a good list of every single landing craft I can name
LCA: Landing Craft, Assault
LCC: Landing Craft, Control
LCF: Landing Craft, Flak
LC(FF): Landing Craft, Flotilla Flagship
LCI: Landing Craft, Infantry
LCI(L): Landing Craft, Infantry Large
LCM: Landing Craft, Mechanized
LCP: Landing Craft, Personnel
LCR: Landing Craft, Rubber
LCS: Landing Craft, Support
LCS(S): Landing Craft, Support Small
LCT: Landing Craft, Tank
LCT(R): Landing Craft, Tank Rocket
LCV: Landing Craft, Vehicles
[The oh so popular and well known] LCVP: Landing Craft, Vehicle, Personnel
I've done some researching and found out that In the Rhine Valley, when the Lundendorff Bridge at Remagen was destroyed by German Artillery just after american armored units crossed it, archival footage showed heavy duty trucks hauling in LCP's and LCVP's and then embarking across the Rhine, so the sea may not be the only place these Landing Craft were used.
EDIT1: Postscript, I hate to break it to you all but um, isnt this thread about introducing Landing Crafts to AH and not about P51's Ruling