On the left, there is a list of options. Click “Cross-Chain”
Choose the “C Chain (Contract)” as the destination chain
Enter the amount you would like to transfer, and then click confirm.
Now that the conditions of the transaction have been set, it's time to send the AVAX from your Avalanche Wallet to MetaMask.
Select "C Contract" as the Source Chain
Enter your MetaMask wallet address by copying and pasting it into the “To Address” field on your Avalanche wallet.
Confirm and finalize the transaction.
Since June 2021, KuCoin has opened the contract chain (C-Chain) deposit and withdrawal services for Avalanche (AVAX). This allows users to skip the process of getting an additional Avalanche Wallet to move your assets from the X-Chain to the C-Chain.
Head over to Assets> Main Account> Deposit/Withdrawal page and select the AVAX (C-Chain) network for transactions.
Since June 2021, Gate.io has opened the contract chain (C-Chain) deposit and withdrawal services for Avalanche (AVAX). This allows users to skip the process of getting an additional Avalanche Wallet to move your assets from the X-Chain to the C-Chain.
cBridge (beta) powered by Celer Network
To bridge usdt directly between polygon and avalanche, one can use the cBridge by Celer Network. You will need to have some avax first on your wallet connected to the avalanche network, otherwise your funds might stuck.
ElkNet Cross Chain Transfers (Beta)
Elk Finance has a Cross Chain transfer capability in Beta that works well for transferring funds from Binance, Polygon, and Fantom to name a few.
A few things to remember when using this route:
Has to be in $ELK
Maximum of 2000 $ELK
It will even allow you to swap 1 $ELK for Gas
Once you've initiated the transfer from the source chain. Switch to Avalanche and then exchange your $ELK for $AVAX, and you're ready to start exploring.
Avalanche Bridge (Beta)
The Official Avalanche Bridge will allow you to transfer over funds from Eth Mainnet to Avalanche, and if you convert more than $75 worth of any token, they'll airdrop in some AVAX to help you get started with gas costs on the other side.
You are also able to convert back from Avalanche to Eth the same way, as well as see the proof of asset available for transfer. Allowing you to track it through the AVAX C-Chain Explorer
Congratulations! You now have AVAX on your MetaMask wallet and can start using Avalanche.
Always be careful, always do your due diligence, and please always review the current documentation for the above recommended routes at their respective sources to ensure you are successful.