Carts pretty usefull. Just don't try haul it full of ore, fill maybe like 5 or 6 spaces with ore and whatever you can carry on you, still allows you to move about 3 to 5 times more in one run. The weight limit isn't affected when swimming with it so you could plan a swimming route back to your base

If playing multiplayer just have a friend sit in the cart while carrying all the ore and you can pull the cart easy peasy back to base full of tonnes of ore