The number of warrants exercised during the period.

No definition available.

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

- Definition

The number of warrants issued during the period.

+ References

No definition available.

+ Details

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

- Definition

The minimum threshold period during which a written notice is required for redemption of warrants, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Threshold period for calculating the average closing price of a common share for the purpose of redemption of warrants.

+ References

No definition available.

+ Details

Name:	tmc_ThresholdTradingDaysForCalculatingAverageClosingPrice
Namespace Prefix:	tmc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The issuance price of additional capital which would trigger an adjustment in the exercise price of the warrant.

+ References

No definition available.

+ Details

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

- Definition

The number of consecutive trading days within a specified range when the reported sale price must exceed the specified amount.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Number of warrants or rights outstanding.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

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

+ Details

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

- Details

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

- Details

Name:	srt_StatementScenarioAxis=tmc_RedemptionOfWarrantsWhenPricePerShareOfClassCommonStockEqualsOrExceeds18.00Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Warrants - Public and Private Warrants (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) D $ / shares shares	Dec. 31, 2024 USD ($) shares	Oct. 09, 2021 $ / shares
Warrants
Issue price per share \| $ / shares	$ 18
Trading days for redemption of public warrants	20
Consecutive trading days for redemption of public warrants	30
Public Warrants
Warrants
Number of warrants outstanding \| shares	15,000,000
Number of warrants exercised \| shares	0	15,000,000
Number of warrants issued \| shares	0	15,000,000
Exercise price of warrants \| $ / shares	$ 0.365		$ 11.5
Redemption price per warrant (in dollars per share) \| $ / shares	$ 0.01
Minimum threshold written notice period for redemption of public warrants	30 days
Trading days for redemption of public warrants	20
Consecutive trading days for redemption of public warrants	30
Threshold trading days for calculating the average closing price	10
Value of outstanding warrants \| $	$ 19.5	$ 19.5
Public Warrants \| Redemption of warrants when price per share of class common stock equals or exceeds 18.00
Warrants
Issue price per share \| $ / shares	$ 18
Private Warrants
Warrants
Number of warrants outstanding \| shares	9,500,000	9,500,000
Redemption price per warrant (in dollars per share) \| $ / shares	$ 0.01
Threshold trading days for calculating the average closing price	10
Value of outstanding warrants \| $	$ 13.4