A locking tree cap for use on a subsea tree. The tree cap may be installed and retrieved using a remote operated vehicle. The tree cap may include deflectable collet fingers that lock the tree cap to a tree spool. The deflectable collet fingers may be adapted, such as with enlarged heads, to extend into recesses of the tree spool when the tree cap has been landed on the tree spool. The tree cap may be locked onto a tree spool before energizing sealing members within the bores of the subsea tree, thereby protecting the sealing members from damage during the installation of the tree cap onto the tree spool. The tree cap may include soft landing means such as a plastic cap, on the end of stabs to protect the sealing members as the tree cap is landed. The tree cap may include a secondary locking mechanism used to further secure the tree cap to the tree spool.