Bridging SEAM Between Base and Ethereum Mainnet

Choose between these three simple options to bridge SEAM between Base L2 and Ethereum Mainnet

Introduction

With the launch of SEAM on Base, the community has also introduced a bridged version of SEAM via the canonical Base Bridge.

With the existence of multiple bridging paths for SEAM, this article plans to outline a few of the different ways to bridge SEAM between Base and Ethereum and vice-versa.

Note: Information on smart contract addresses for SEAM can be found in the gitbook here.

Bridging Options

The following are bridging options with a brief description and how-to guide.

[1] Centralized Bridges — https://www.gate.io/

Centralized bridges exist, most notabley centralized exchanges like Gate.io, which allow users to deposit and withdraw across both chains, Base and Ethereum Mainnet. This means users can follow typical Gate.io procedures to deposit SEAM from one chain, and withdraw on another. Users are advised to do their own research and check liquidity and the technical status of the Gate.io platform as it is possible due to maintenance or other issues that withdrawals and deposits can be temporarily suspended. The time estimate for this type of bridging is purely based on the centralized provider’s processes (i.e. Gate’s deposit and withdrawal processes).

[2] Cross-chain Swapping — https://app.squidrouter.com/; https://jumper.exchange/

Cross-chain swapping, popularized by projects like Axelar and Stargate, are also an option for bridging assets. When cross-chain swapping, users swap their original asset for a bridge-able asset, which is transferred to the destination chain and swapped back into the original asset. If that sounds confusing — don’t worry — interfaces such as Squid Router (built on Axelar) and Jumper Exchange (Li.Fi), make this process a breeze! Users are advised to check to do their own research and check for slippage and liquidity depth when choosing this approach. The time estimate for this approach is fairly fast, with some swaps happening in a matter of seconds, depending on the route that a cross-chain swapper chooses.

To read more about this approach and a step-by-step guide on Squid Router, view this previous blog post for more details.

[3] Canonical Base Bridge — https://bridge.base.org/deposit

With SEAM’s recent launch, the official Base Bridge UI has not been able to keep-up and update it’s interface to reflect the bridged SEAM asset.

However, users can still easily bridge SEAM from Ethereum Mainnet to Base using the official Base Bridge via direct smart contract calls on etherescan. Here are the steps below:

1. Navigate to https://etherscan.io/address/0x6b66ccd1340c479B07B390d326eaDCbb84E726Ba#writeContract and connect your web3 wallet to Etherscan
   a) You should now be on the contract → write contract tab with your wallet connected.
   b) This connected wallet should also be connected to Ethereum and hold the SEAM you would like to bridge
2. After connecting your web3 wallet of choice, select function #1, called approve, and for the two fields, you must input:
   a) spender: 0x3154Cf16ccdb4C6d922629664174b904d80F2C35
   b) value: amount of SEAM you want to bridge, this is in raw 18 decimal format so 1 SEAM = 1e18
   c) Click “write” and approve transactions accordingly in your web3 wallet (make sure you are connected to Ethereum)
3. Now you need to call BridgeERC20To (write as proxy) on the Base Bridge contract, to do this, navigate to: https://etherscan.io/address/0x3154Cf16ccdb4C6d922629664174b904d80F2C35#writeProxyContract#F2 and once again connect your wallet to Etherscan (if it is not already connected)
   a) You should now be on the contract → write as proxy tab with your wallet connected.
   b) This connected wallet should also be connected to Ethereum and hold the SEAM you would like to bridge
4. After making sure you have selected function #2 (BridgeERC20To), you. must fill out the fields found within the function with the following information:
   a) _localToken: 0x6b66ccd1340c479B07B390d326eaDCbb84E726Ba
   b) _remoteToken: 0x1C7a460413dD4e964f96D8dFC56E7223cE88CD85
   c) _to: address on Base you want to send SEAM to
   d) _amount: same amount that was specified as the value in the approve call in step 2b.
   e) _minGasLimit: 100000
   f) _extraData: {leave this empty}

Screenshots below:

Steps 1 and 2 above should have this view in etherscan

Steps 3 and 4 should have this view in etherscan

Conclusion

With SEAM’s rapidly growing community, there are now also many options for bridging SEAM across a growing footprint of Base and Ethereum.

More options are constantly being developed and supported by the community, check back here for updates and details (such as official Base Bridge UI support). If there are additional options that were missed, share it to the community in Discord or Telegram (links below)!

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Join the community and get plugged in via the following links:

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