Jumping two blocks high?

Here are your options:

• If there's a horse, a saddled pig, a boat, a minecart or a bed (only during the night) nearby, you can try to right-click it; this will teleport you out of the hole. If you have a boat or minecart with you, you can jump and place it down outside the hole - they are entities, not blocks.

• If you have an Enderpearl, throw it (right-click) to get teleported wherever it lands. Don't throw it straight up or against the hole walls though ...

• If the game has environmental dangers you or other players can manipulate (flowing water or lava into the pit or dropping a single block of gravel or sand into it), you can use it. Same for pushing the lower block of the hole into you.

• If the game has custom potions with the "Jump Boost" effect (at least level 2), custom enchanted items with the same, a nearby beacon giving this power or can give you the effect via command blocks, you can use it to gain additional jump ability.

• You can wait for an Ender Dragon to destroy some blocks around the hole, for an Enderman to randomly decide to pick a block off the edge of the hole or a Creeper to blow up nearby. This could be a long and potentially deadly wait.

Being a server admin on a server that prevents building in certain areas, I've found my users to be the best guinea pigs for this kind of question, and Long Ago one of mine introduced me to double-jumping:

With the lag inherent in Minecraft servers, you should be able to jump and place a block beneath yourself. In the split-second that the client allows you to place the block and the server hasn't announced that you can't, you should be able to leap off of it and escape. It takes split-second timing, so don't give up if it doesn't work the first time.

If you can break blocks but they immediately respawn, then you can try destroying one block (the upper one) while jumping against it if you do it correctly you are stuck between the lower block and the upper block. After that you simply have to jump once without pressing any direction keys and voila, you are free! Works for me on almost all servers I have been to and can be "abused" for several other things.

No, you're probably going to have to get ahold of a moderator or an admin on the server. Jumping two blocks high is not possible unless you use the /effect command to give yourself a jump boost.