Del. Code Ann. tit. 7, § 4519
Title or interest in public lands obtainable only by deed, conveyance or written instrument
63 Del. Laws, c. 401, § 1;
No title or other interest in real property belonging to the State shall be acquired by adverse possession, presumed grant or any means other than by a deed or conveyance or other written instrument of transfer executed by a duly authorized official of the State pursuant to state law.