Area of land for which applications submitted to secure commercial recovery.

No definition available.

Name:	tmc_CommercialRecoveryAreaOfLand
Namespace Prefix:	tmc_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of land for which applications submitted to secure exploration and commercial recover

+ References

No definition available.

+ Details

Name:	tmc_ExplorationAndCommercialRecoveryAreaOfLand
Namespace Prefix:	tmc_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of land for which applications submitted to secure exploration license.

+ References

No definition available.

+ Details

Name:	tmc_ExplorationLicenseAppliedAreaOfLand
Namespace Prefix:	tmc_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Period of extension of exploration contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of application made for exploration licenses

+ References

No definition available.

+ Details

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

- Definition

Represents the number of application made for exploration licenses.

+ References

No definition available.

+ Details

Name:	tmc_NumberOfApplicationForExplorationLicenses
Namespace Prefix:	tmc_
Data Type:	xbrli:integerItemType
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-20

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 20
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-20

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 55
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477916/932-235-55-4

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-17

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 19
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-19

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-18

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-18

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 932
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477215/932-235-50-18

+ Details

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

- Details

Name:	dei_LegalEntityAxis=tmc_NauruOceanResourcesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=tmc_NoriExplorationContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=tmc_TongaOffshoreMiningLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=tmc_TongaOffshoreMiningLimitedExplorationContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Nature of Operations (Details)			1 Months Ended
Nature of Operations (Details)	Jul. 20, 2026	Jul. 10, 2026	Jul. 31, 2026	Apr. 28, 2025 km² item
Nature of Operations
Number of applications for exploration licenses \| item				2
Number of applications made for commercial recovery permit. \| item				1
Area of land for exploration license (in square km)				187,017
Area of land for commercial recovery (in square km)				25,160
Area of land for exploration and commercial recovery				65,000
NORI \| NORI Exploration Contract \| Subsequent event
Nature of Operations
Contract extension period	5 years		5 years
TOML \| TOML Exploration Contract \| Subsequent event
Nature of Operations
Contract extension period	5 years	5 years	5 years