Bottom conditions will help you determine what anchor to use and the quality of the holding conditions.

Never anchor on coral - it is illegal and seriously damages the coral and the surounding eco system.

Danforth Anchor: If anchoring on a sandy or muddy bottom you will want to use a danforth anchor. The flanges on a danforth anchor can dig well into a sand or mud bottom providing a secure hold. The Danforth is not effective in weed or rock bottoms.

Plow Anchor: The plow anchor is a good all purpose anchor. It is best for mud or clay bottoms but still has good holding qualities in sand. In weed it holds reasonably well but is not good in rock.

Bruce Anchor: The Bruce anchor is another good all purpose anchor. It works well in silt bottoms, may hold in rock but is not good in weed.

Grapnel Anchor: The grapnel anchor is good in rock and is generally onboard as a secondary anchor. It is not good in mud, clay or sand bottoms.

Fisherman Anchor: The traditional looking fisherman anchor is good in rock and weed. Again, this anchor is kept on board as a secondary anchor.

It would be unreasonable to carry onboard all the anchors mentioned. Generally most sailors will have two anchors on board and depending on the area they are sailing, most opt for the Danforth plus either the Plow or the Bruce anchor.