This mod can replace others maps aside from the beach farm, but it is the one I replace and recommend replacing. 
Features:

• Hidden Custom Location to visit along with the Farm Cave.  (Will not provide spoiler, so don't ask.)
• Accessible Palm Trees
• Standard Beach Farm features, such as supply crates and ocean fish.
• Most of the map is diggable
• Sandy Areas allow sprinklers
• A small pond next to the Farmhouse for refilling the watering can.
• A small Quarry accessible via FarmCave
  

Farm Cave Features:

• Brings some Ginger Island flare with fish from the island.
• Spa water to swim in. 
• Acts like a greenhouse in dirt spots.
• Caskable
• Foragables, in addition to the fruit or mushrooms.
• Artifacts to find
• Functional Minecart
• Secret Woods theme
  

This map will, for the above reasons, be a little overturned. For this reason, the extensive farming area is restricted initially, as most of the map will be inaccessible without tool upgrades or a pain to utilize. It's also adorable. This map was made for my significant other, so don't expect much regarding user support, compatibility issues, etc.

Installation:
Extract folder into mods after installing Smapi, DaisyNiko's Tilesheets, and Content Patcher. Uses custom tilesheets.

FOR STARDEW VALLEY EXPANDED USERS:
The nexus warp point should be edited in \Stardew Valley\Mods\[CP] Stardew Valley Expanded content.json to do this, open the content.json and find //Beach Farm - A quality parsnip. Replace with the following and save:
{  //Beach Farm - A quality parsnip
   "Action": "EditData",
   "Target": "data/events/Farmhouse",
   "When": { "FarmType": "Beach", "HasSeenEvent|contains=908072": true },
   "Entries": {
   "908074/t 600 2600": "continue/-500 -500/farmer -50 -50 0/skippable/pause 1000/changeLocation farm/warp farmer 72 28/faceDirection farmer 0 true/makeInvisible 72 25 1 3/viewport 72 27 clamp true/pause 2000/showFrame farmer 15/pause 100/startJittering/pause 250/addObject 72 25 24/playSound stoneStep/playSound stoneStep/pause 300/stopJittering/pause 230/showFrame farmer 12 true/pause 1500/playSound dwop/showFrame farmer 65 true/pause 1250/screenFlash 1/playSound wand/playSound wand/removeSprite 72 25/addLantern 1000 72 25 1/addTemporaryActor MagicWarp 48 48 72 26 2 false/positionOffset MagicaWarp 7 -6/pause 400/showFrame farmer 12 true/pause 350/playSound secret1/pause 2500/globalFade/viewport -1000 -1000/end"
   }
},
{   //Beach Farm  - statue warp graphic
    "Action": "EditMap",
    "Target": "Maps/Farm_Island",
    "FromFile": "assets/Maps/MapPatches/EnchantedGrove_Farm.tbin",
"ToArea": { "X": 71, "Y": 24, "Width": 3, "Height": 3 },
    "When": { "FarmType": "Beach", "HasSeenEvent": "908074" },
"Update": "OnLocationChange",
"PatchMode": "Overlay"
},
{   //Beach Farm  - Patches warp point on farm
    "Action": "EditMap",
    "Target": "Maps/Farm_Island",
"When": { "FarmType": "Beach", "HasSeenEvent": "908074" },
"Update": "OnLocationChange",
    "MapTiles": [
      {
        "Position": { "X": 72, "Y": 25 },
        "Layer": "Back",
        "SetProperties": {
        "TouchAction": "MagicWarp Custom_EnchantedGrove 30 14"
      }
    }
  ]
},
{   //Beach Farm  - statue light
    "Action": "EditMap",
    "Target": "Maps/Farm_Island",
    "When": { "FarmType": "Beach", "HasSeenEvent": "908074" },
"Update": "OnLocationChange",
    "TextOperations": [
     {
      "Operation": "Append",
      "Target": [ "MapProperties", "Light" ],
      "Value": "72 25 4",
      "Delimiter": " "
     }
   ]
},
{   //Beach Farm  - Patches warp point at enchanted grove
    "Action": "EditMap",
    "Target": "Maps/Custom_EnchantedGrove",
"When": { "FarmType": "Beach", "HasSeenEvent": "908074" },
"Update": "OnLocationChange",
    "MapTiles": [
      {
        "Position": { "X": 30, "Y": 14 },
        "Layer": "Back",
        "SetProperties": {
        "TouchAction": "MagicWarp Farm 72 25"
      }
    }
  ]
},