Name:	tmc_ClassOfWarrantOrRightMinimumThresholdWrittenNoticePeriodForRedemptionOfWarrants
Namespace Prefix:	tmc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Redemption price per share or per unit of warrants or rights outstanding.

No definition available.

Name:	tmc_ClassOfWarrantOrRightRedemptionPriceOfWarrantsOrRights
Namespace Prefix:	tmc_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

The number of warrants issued during the period.

No definition available.

Name:	tmc_ClassOfWarrantOrRightWarrantsIssued
Namespace Prefix:	tmc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The threshold volume weighted average price as a trigger for warrants cancellation.

No definition available.

Name:	tmc_ThresholdVolumeWeightedAveragePriceTriggerForWarrantCancellation
Namespace Prefix:	tmc_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

The number of trading days over which the reported sale price is measured when determining the redemption price.

No definition available.

Name:	tmc_WarrantRedemptionMeasurementPeriod
Namespace Prefix:	tmc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The amount of expenses associated with warrant issuance.

No definition available.

Name:	tmc_WarrantsIssuanceCosts
Namespace Prefix:	tmc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of increase in additional paid in capital (APIC) resulting from the issuance of warrants. Includes allocation of proceeds of debt securities issued with detachable stock purchase warrants.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-SubTopic 10
-Topic 505
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481284/470-20-25-2

Name:	us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Exercise price per share or per unit of warrants or rights outstanding.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(4))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-3

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ClassOfWarrantOrRightLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares.

No definition available.

Name:	us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number of warrants or rights outstanding.

No definition available.

Name:	us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Name:	us-gaap_WarrantsAndRightsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Name:	us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_ClassOfWarrantOrRightAxis=tmc_ClassaWarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsidiarySaleOfStockAxis=tmc_RegisteredDirectOffering2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ClassOfWarrantOrRightAxis=tmc_ClassBWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsidiarySaleOfStockAxis=tmc_RegisteredDirectOffering2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ClassOfWarrantOrRightAxis=tmc_ClassCWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_SubsidiarySaleOfStockAxis=tmc_RegisteredDirectOffering2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ClassOfWarrantOrRightAxis=tmc_KoreaZincWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ClassOfWarrantOrRightAxis=tmc_NauruWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: